Spent absolutely ages on the Internet looking for a camera bag which would protect the camera, give quick access when the 'perfect shot' presented itself, and have room for keys, purse, lunch and other stuff for a day out. Lowepro have a mind-boggling selection to choose from but I chose the Fastpack because it seemed the most practical for my needs, and the 200 size is a good size. My only concern before buying it was that if it it was quick access for me, it might also be very easy to steal the camera in a crowded tourist place. It's not obvious from the photos but there is a flap which can clip down over the camera compartment. So if the zip for the camera is closed at the top it is impossible to get to the camera easily, making it pretty secure in busy places.
This bag is very very, good quality, has plenty of little pockets all over the place, a drink holder on the side, loads of space for your own stuff, is well padded and very comfortable to carry. I just have a Nikon D300 + a telephoto, but there's still room for another couple of lenses. The clever velcro system means you can move the sections around to fit your gear. This is absolutely perfect for the average amateur photographer. The only thing missing which is on higher end bags is a holder for a tripod, but I could fit straps on if I decided I need this. A final good feature (I think) is that this just looks like your average rucksack, it doesn't shout 'camera & expensive gear worth pinching'.