I just upgraded to the Canon 7D from the Rebel xTi and have had only a few minutes to play with it. But I am already thoroughly impressed. A couple features that are blowing me away:
1. ISO to 6400. Wow. This will really help in low light situations.
2. Auto adjust of ISO. Truly amazing! you can set it to auto adjust your ISO the same as Shutter and Aperture. Wow.
3. Second wheel for adjusting Aperture. Now in full manual mode, one wheel for shutter, one for Aperture. Makes it so much easier and faster.
4. Three customizable Modes!!! Just like switching to full auto, full manual, or in between, you can pre-define 3 different custom settings and just switch to them instantly. What a life saver.
5. Video. Super cool!
The 7D is just such an amazing precision camera. I am in love already after only a few minutes. And I haven't even learned the insides and out yet.
For anyone thinking of upgrading, it is a ton of money, but so worth it!!! I can't wait to see it in action at Disney this Oct.