Having spent the past week working with footage from a Canon 7D — grading it, and also compositing with it — I have to say that it looks great … right up to the point where it doesn't any more. The stuff I worked with this week had less than a stop of latitude in either direction. If I pushed it even a little bit, it was digital noise as far as the eye could see.
Now, that may not be an inherent factor of the camera. The stuff I had to work with was very under-lit overall (and poorly lit in general), and came off the camera way too saturated, with objectionable moirés and aliasing everywhere. There were certainly lighting decisions on-set that contributed to the problems, and possibly there are in-camera settings that could be tweaked as well.
But apart from that, the stuff looked good. Better, certainly, than what you'd get of XDCAM EX or HDV.