Just got a chance to handle the camera and shoot a few test images. Not enough to evaluate image quality yet, but I wanted to share my initial impressions of the physical package... favorable. A few things stand out:
1) The viewfinder is far and away the best Canon has ever put into a small-format SLR I think. The image is big a bright, really leaps above the 50D. Without having a chance to compare side by side, I'd say it is at least as good as the 1D3 viewfinder, maybe better. The area AF array is very similar in feel to that in the 1-series cameras, as the AF points light up only when active, giving a nice clean view. All that, coupled with use of the same viewfinder eyepiece as the 1-series, makes this camera feel a lot like a "baby 1D3".
2) The rear LCD is even brighter, clearer and more easily viewed in bright conditions than that on the 5D2. It's nice to see Canon continuing to improve this.
3) Heft, feel, overall construction quality: definitely solid. The salesman I discussed this with offered his opinion that it "feels like a D300". Having owned a pair of those, I'd have to agree. This camera blurs the line between "pro" and "prosumer" more than any previous non 1-series Canon body I think.
4) I like the position of the new on/off switch, which is good, as it is likely we'll see on future models.
So overall, a good first impression. No chance to test focus yet, or look at images carefully though... More anon.