Being not a videographer but a photographer (it's not a camcorder, after all...

), I am more interested in photography-oriented features, in particular the adjustable Auto ISO that the 550D has.
It was quite a surprise when that feature jumped from the 1D series directly to the Rebels, skipping the "enthusiast" models (5DII, 7D) in between. But its an outright audacity from Canon's side NOT to find some time to add this highly useful feature also to the 5DII/7D with a firmware update. ISO3200 (the 7D's default and "hard-wired" upper boundary for its auto ISO functionality) is just too noisy for my taste on the 7D.