So mine arrived today ... after the delay last month. This is my first tablet so I don't have much to compare it with - however I have come from a Android phone and I much prefer Android to the Iphone - hence my decision on this tablet. This is very much a first impression view.
When I switched it on, I had 2 firmware updated to do, one for the tablet and one for the keyboard - they only took 5 minutes.
Docking the screen into the keyboard was a little scary, however after reading the manual, and found the release catch, it slotted in with a satisfying click. The keyboard itself is really very good. It was the fact it has the keyboard that prompted me to get this one, because it's just so much easier to write docs, emails etc. Once it's docked, you get added benefits too, like doubling the battery life, access to 2 standard USB ports and a standard SD card slot. You can also put a microSD into the screen part itself, so while travelling, you're not limited to taking a few movies, you literally can take a handful with you.
As I have an Android phone, after hooking it up to my wi-fi and logging in with my gmail account, all the apps I was used to, auto downloaded. In the Google Market place website, your device will appear and you can pick apps and have them sent to your tablet over the air, just as you can with the phone - however I have noticed that some apps weren't available - such as Need for Speed (which would have been cool on the big screen) but I'm sure it'll be ported soon enough. Unlike Iphone apps running on the Ipad in a small letterbox in the center of the screen, Android apps that haven't been ported for the Tablet, still look fine, because they take up the whole screen anyway and space their content our accordingly.
Web browsing is a great experience. I'm just using the stock browser at the moment, but with Flash support, sites like the BBC news site are complete with in page video etc. I noticed that you don't get redirected to the mobile site ... for example, Facebook, so you get the full site, which always annoyed me a bit on my phone.
For more work related apps, it comes with an Office variant, which seemed to open the 2 MS Word documents I tested (2003 and 2010) and they maintained all of the formatting including tables, book marks, images etc. The keyboard is nice to work with and I don't think it'll become a problem - seems sturdy enough and doesn't feel any different to a notebook keyboard.
In my role as a IT nerd, I am hoping that I can take this with me on site and hook into serial ports of servers via the USB or via bluetooth serial plugs and provision systems (with the built in telnet client) without the need to lump a full sized laptop around with me.
I haven't really used it in anger yet, but it covers everything I have wanted to do with it so far. I have had one die hard Apple fan moaning that the screen switching isn't as smooth as the ipad - but the iphone was always smoother that the Android phones. Looks like Apple have put so much effort into animation, they forgot to make it compatible with anything else. (did I mention bluetooth? :))
I don't know if there will be a 3G version, but I'm happy to use my phone as a wifi hotspot if I need the net while I'm out and about.
So, in summary - if you are considering an Ipad - then you should really think about this as a valid alternative. If you're already an Android user - this is a no brainer.