got mine a couple of days ago, massive upgrade from my 600D
The thing focuses like crazy in low light - I'm primarily a nightclub/social photographer
not a pixel peeper, but the IQ, even at 12800 easily fits my needs
Yet to test the GPS, however the wi-fi feature is pretty handy. Unlike the Eye-fi cards, when connected to a phone via wifi/app, doesn't transfer the photos automatically, instead you have to "pull" the photos from the camera - suits my needs better than the eye-fi method, but when connected to a computer will transfer everything.
Operation is very similar to working with the 60D, with a few elements of the 7D (I work in a camera store, so I get a chance to play with pretty much anything)
still haven't had it long enough to fully understand the way the camera work - but I'm quite happy with it