Let's go with the positives first.
- Builtin GPS & Wireless, no need for ultra-expensive add-ons. Nice!
- Full-frame with ISO down to 50, something my 7D can't do. Nice!
- Same battery packs as the 5D and 7D, very useful, for me at least.
- Some other small nifty features that sound nice, WB-bracketing etc.
- Viewfinder at 97%, why? My 7D does 100% and I like it.
- 11 AF points, don't know enough to say whether they are good or "bad", but seems awfully "underpowered"
- No builtin flash, I use the builtin on the 7D to command remote flashes and it is quite a valuable feature for me.
- No CF, massive bummer for me, can't swap cards between cameras.
My verdict: As I have the 7D, this offers no reason compelling enough to go for this model. I will keep my sights on getting a 5D3 instead when I finally do go full-frame. OR, god forbid I become rich and can get me the 1D-X.
But for someone starting out, why not? Certainly the list-price is high, but does anyone ever pay list-price?
The way I see it is that, yes, it may be a let down for most people on this forum, but if I was just getting my DSLR now, I might go for this. Especially since a lot of my friends shoot Canon, which means I have access to a nice spectrum of lenses.
On another note, I haven't seen anyone yet that actually made the switch to Nikon, lots of threats, but seem more like a knee-jerk reaction to me. Yes, the Nikon sensor may be technically more advanced, but to me useability rates higher than pixel-peeping. Almost every Canon camera I've seen so far produces good images in the right hands.