Things I like about the 400D/XTi:
- 10 megapixels - more is better, right?
- dust removing shake-off of sensor
- new sensor - lower noise, apparently
- bigger LCD
- large continuous shoot buffer - twice as many rapidfire shots
- eyepiece sensor shuts off LCD automatically when you hold the camera to your eye
- RGB histogram, in addition to luminance
- slightly less costly than the XT
Things I don't like about the upgrade:
- lack of second LCD. it was dropped, I assume, to make room for the bigger main LCD, but it's really nice having the separate (dimmer) LCD for main settings without having to power up the main LCD. This is especially nice when shooting at night, when the bigger brighter LCD blows your night vision away, while the smaller, dimmer, orange-glowing secondary LCD on the 350D/XT is nice and handy
- my XT is technically obsolete. stupid progress...
So, while more pixels, and a cleaner (physically and image-wise) sensor are nice, the lack of the secondary LCD kinda sucks. But, the 350D/XT is still more camera than I know what to do with (yet) so I have absolutely no regrets. I didn't think I'd be able to say that after my XT became obsolete, but I'm still loving my camera. However, if Canon wants to send me a 400D/XTi upgrade for my 60-day-old 350D/XT, I won't complain... I'm curious to see how this new model stacks up against Nikon's new D80, as well.