This is what I wanted in a DSLR. I liked my old 10D very much and used it often. But I was going to go back to my EOS 3 and slides until the 5D came along.
The images are sharp with any of my lenses. I only have Canon lenses now. The camera responds predictably to setting changes. The Picture Styles feature is nice for B&W shots and landscapes (I'm not a portrait guy).
I have a very fast and powerful PC, and a very good laptop. If not, I think processing RAW images would be a chore.
I've got 2 2GB CF cards and 2 1GB CF cards. Even at 5D scale they are still the equal of a lot of rolls of Fuji. The buffer is big and the card access is fast. I have not over run it in burst mode, yet.
Some of the things folks have said about buttons and features would be nice. But for me, the full frame, speed, and the image quality more than make up for anything I read here.
A built-in flash would be welcomed, but the EOS 3 doesn't have one either.