(I'm putting a quick update at the top, for those who don't get a chance to read all the way through. As of 03/14/2013 my 7D is still working perfectly, and only has slight cosmetic wear on the mode dial, where the rubberized coating is coming off. The camera is about 3.5 years old at this point.)
The Canon EOS 7D is Canon's semi-pro / enthusiast digital crop sensor SLR. It's a terrific SLR that shines in photo quality, control placement, speed, and viewfinder size and coverage.
First, let me tell you a little about myself so you can gauge what my expectations for the camera are. I'm strictly a hobbyist photographer and use my camera a couple of times a month at museums, outdoor parks, and vacations. Besides photos of my dog, my photography consists primarily of static subjects. This is my second SLR.
Enough of me, onto the camera. The 7D is a fairly bulky SLR and dwarfs "entry level" models such as the Olympus E-510 (see my photos), though it's no bigger than Nikon's D300s. With that said, it's not uncomfortably large and is easy enough to carry around all day. Build quality is terrific and the camera has a solid, luxury feel to it. The 7D fits very well into my average sized hands and, with the kit 28-135 lens, is nicely balanced. All the buttons are easy to reach and, if you've used a Canon camera before, easy to figure out. The magnesium body is sealed against moisture and dust. The shutter button is well placed and has a nicely defined halfway point. A control dial is on the back of the camera and behind the shutter button too. There is also a joystick-like toggle on the back of the camera as well.
A large (3") and high-resolution (920,000 pixel) screen is on the camera back with a secondary status LCD display on the top (with backlight). The screen is a pleasure to use when reviewing images for focus, and when manually focusing in magnified live view mode. Compared to the 3-inch 420,000-pixel screen on my Panasonic LX3 it's a definite upgrade, and makes a noticeable difference.
The viewfinder is huge and bright and has 100% coverage. Coming from the Olympus, which has a very cramped and tunnel-like viewfinder, it was a revelation, and was one of the reasons I decided to step up to the 7D. Also, by using a transmissive LCD on the viewfinder the only markings you see until you confirm focus are for the selected focus method (for instance, a single box when using one focus point, or brackets when using the auto select autofocus method). Moreover, a composition grid can be imposed on the viewfinder. The information display on the bottom of the viewfinder is large and bright and contains lots of shooting and camera information.
The camera is very responsive and turns on almost instantly. The sensor cleaning occurs when you turn the camera on or off but can be interrupted during power up. Focus speeds with the kit lens are very speedy, even in dim light (two 40 watt lamps and a television as the only light sources in a 17' x 11' room). The 19-point all cross type autofocus is uncanny at picking the correct subject. If it doesn't get it right the first time it will the second. I usually set all my cameras to center point autofocus, but the 7D does a great job picking out the subject, so I leave it on fully automatic mode (unless I'm using the 50mm f/1.4 lens, since wide aperture lenses like that can focus shift with such a shallow depth of field). Live view focusing is not a quick, especially in low light, and I only use live view when I need to shoot at a weird angle and I can't shoot looking through the viewfinder. Live view can be used with a mirror flip or contrast detection. The contrast detection mode is fairly pokey, while the mirror flip mode is quicker, but introduces a brief break in the view. Continuous shooting is available in both a high and a low setting. High is 8 FPS, while the low speed is 3 FPS. The shutter sound is nicely subdued and not nearly as noisy as the Olympus' is.
Photo quality is terrific. There are various Picture Styles you can choose to alter the contrast, sharpness, color tone, and saturation of the photos. At any rate, 99% of the time, colors are natural, exposure is accurate, and dynamic range is great. At this level of camera, that's expected though. What I really love about the 7D is the high ISO noise, or lack thereof. The luxury of feeling confident while shooting at high ISO is priceless. I've taken a good number of shots as high as ISO 3200 and have no complaints. Of course there is a bit of noise, and the mushiness that noise reduction brings, but for an 18 MP image at ISO 3200, I have no complaints. The ISO speeds above 3200 are OK as well, but I'll reserve those for emergency use only, they get fairly processed looking. (Updating this section a bit: Since the 7D is over 3 years old at this point its high ISO shooting is not as good as it once was relative to the competition. I have a Canon G1 X and the Fuji X100 and they both do a bit better at ISO 1600 and higher. Having said that I doubt anyone would complain about the 7D's high ISO results, but you should be aware that sensor technology has gotten better since the 7D was introduced.) The relatively large APS-C sensor not only allows for low noise, but also allows me to produce nicely blurred backgrounds and great depth of field. I couldn't achieve the same degree of that effect with the smaller 4/3 sensor in the Olympus, and I certainly couldn't do it with my point and shoot cameras unless I was in macro mode. There is an Auto Lighting Optimizer feature that attempts to correct photos that are hard to correctly expose (e.g. big difference between shadows or highlights in a scene). It works well for the most part, but, depending on the subject, the differences are very subtle. There is also an image highlight tone priority option available in the menu system that limits the lowest ISO setting to 200 and helps preserve highlights a bit, but it too, is subtle.
The HD movie mode is nicely done as well. You set your focus, either automatically or manually, before you start recording. You can refocus during recording but you'll definitely notice it. You can adjust shutter speed, aperture, and ISO in manual movie mode as well. There is a monaural microphone on the front of the camera, or you can plug in a stereo microphone. By pressing the shutter button, you can interrupt the movie briefly to take a still photo, similar to Canon's S series super zoom cameras.
The 28-135mm kit lens is nicely constructed and fairly sharp from corner to corner. Purple fringing is not much of a problem in my photos. The field of view is kind of narrow though. The lens starts at 44.8mm with the 7D's 1.6x field of view crop factor taken into account. Without a wide angle it's not an ideal all around lens, but I do feel it's worth the extra money for the kit with this lens. You end up getting a nice, ultrasonic motor, image stabilized, 4.8x lens for a minimal cost.
The only things I don't like about the camera so far are that in auto ISO you can't limit how high it goes (this has been remedied with firmware version 2.0.0 released in August 2012, see below for more details). The other thing I'm not fond of is the fact that when you're in playback mode the most you can zoom out is a 9-image grid. With such a large high-resolution screen I would appreciate an index grid playback mode that showed more photos. Lastly, I find the process for setting the custom white balance a bit long winded. You have to take a photo of a white reference object then go into the menus to choose that photo as the reference photo. On other cameras, even Canon's point and shoots, the process is much faster, and it doesn't save the reference photo to your memory card. It's not the worst system, and I have become very quick at it, but it could be better.
All in all... a phenomenal semi-pro SLR. The Canon 7D covers all the bases.
12/17/2009 Update: I found a nice case for the 7D which fits the camera with kit lens quite well. It doesn't fit much more than that, but it's a good case if you don't carry too many accessories with you. It's the Lowepro Topload Zoom case.Lowepro Topload Zoom 1 Camera Bag (Black)
12/19/2009 Update: You can change the depth of field preview button to switch to another autofocus mode when you hold it down, instead of doing a depth of field preview. I find this very useful since I hardly ever use depth of field preview. Now if I find that the autofocus is consistently not picking the right subject for a shot, I simply hold down the depth of field preview button to have it temporarily switch from auto select mode to spot focus mode. Very convenient.
01/04/2010 Update: Just got back from a trip to the American Museum of Natural History in New York City. The 7D was a joy to use. I took about 160 photographs. Of those only 4 or 5 are out of focus due to camera error. The low light performance continues to impress me. I took many photos at ISO 1600 through 3200 and all of the photos are completely usable. In the large "Sea Life" and "African Mammals" rooms I was able to take sharp pictures of these very dim rooms while shooting handheld at ISO 3200 and no flash (see pictures). Anyone who has visited these exhibits knows how challenging they can be to shoot.
10/20/2010 Update: I am still loving this camera. No problems to report. In fact, I was a little miffed when Canon introduced the 60D because it seemed like I could have saved some money by buying that, however, one of the students in my digital photography class bought one, and while it is a nice camera, the build quality and design are nowhere near the standards on the 7D. Still happy with my purchase.
04/05/2011 Update: Still no problems to report with the camera. I took it out after a recent snow storm when it was still flurrying and it survived just fine.
01/02/2012 Update: Still no problems to report with the 7D. I continue to recommend it.
06/13/2012 Update: The camera still works wonderfully. I've purchased the Canon 24-105mm f/4 L IS USM lens to replace the kit lens as I was looking for something sharper and a bit wider, and the 24-105 does indeed deliver. Build quality and sharpness are much higher than the kit lens. Canon EF 24-105mm f/4 L IS USM Lens for Canon EOS SLR Cameras
07/05/2012 Update: I picked up Canon's new pancake 40mm f/2.8 lens and it makes a great addition to the 24-105 lens. It's small, sharp, and quick to focus. It really does make a huge difference in the 7D's weigh and size and makes carrying the camera on a long hike easy. Canon EF 40mm f/2.8 STM Lens
08/15/2012 Update: I just installed Canon's firmware update version 2.0.0. The update improves many things; maximum RAW burst of 25 images, in camera RAW editing, JPEG resizing, image rating, maximum auto ISO setting, audio level adjustment in movies, GPS compatibility, file name customization, faster scrolling of zoomed images, and quick control screen during playback. The firmware was easy to install and download and took only a few minutes.
08/20/2012 Update: I just picked up Canon's 50mm f/1.4 lens for low light shooting, and it is indeed a great low light friend. The angle of view is a bit tight, but it produces sharp photos with shallow depth of field and nicely blurred backgrounds, especially at f/2.0 and wider. Also, the camera is still working like new and I have no mechanical problems to report. However, a bit of the rubberized coating is coming off of the mode dial. It's very subtle though, and completely cosmetic. Canon EF 50mm f/1.4 USM Standard & Medium Telephoto Lens for Canon SLR Cameras
10/25/2012 Update: I got Canon's 60mm EF-S macro lens and it's a great macro lens. Sharp, small, and quick to focus. I recently took the 7D and my 4 lenses with me to Walt Disney World, took over 1000 photos, and the camera and all the lenses performed great! Canon EF-S 60mm f/2.8 Macro USM Lens for Canon SLR Cameras
04/25/2013 Update: I've also purchased Canon's 28mm f/2.8 IS USM lens and it's a nice compact option that gives the camera a normal view (45º) and has the benefit of an image stabilizer. It makes a great all around / museum lens. It's very sharp and quick to focus. Canon EF 28mm f/2.8 IS USM Wide Angle Lens
P.S.: Sorry for the long review. There is a lot to cover, and even so I may not have gotten everything. If you'd like to know something I didn't cover, feel free to leave a comment and I'll answer it as quickly as I can. Also, I will update this review as needed based on any new experiences I have with the 7D.