I played with a Rebel XSi yesterday.
Things I liked cosmetically.
– Seemed to feel bigger in my hands that the previous 2 Rebels.
* for an entry level camera. It feels a lot better than the Nikon D60 & Sony Alpha 200 in your hands if you have big ones such as myself. I still think the Pentax K200 feels the best.
– Good button placement. i.e. the ISO button.
– Nice VF for a Rebel.
– New grip material
– Red striped strap =D
– The menu system
– The camera setting display is easy to read.
– The IS lens seems to focus fairly quickly.
Things I didn't like.
– New battery. Doesn't appear it'll work on any current universal chargers either.
– Contrast AF in LV isn't great.
– Flash (at least one the one I used) popped up a bit aggressively.
None of this has anything to do with image quality, I didn't have the time for that. The 2 at the store here were both already sold or I may have done some more with it.