It's interesting reading all these opinions. As i'm in the market for a DSLR (or DSLT...) i've been doing a helluva lot of research and with the release of the 6D and D600 have just about decided on an A99 (next year).
I've never used an EVF but this sold me:
http://youtu.be/jPmatcZ99Qw
I mean focus peaking in the viewfinder is a major innovation (exclude downloading Magic Lantern), plus the ability to adjust exposure and zoom in to check focus prior to shooting and without reverting to Live View is superb, ditto adjusting white balance before shooting. Image playback via the EVF - no trying to shade the rear screen to see what you've just shot
Then there's the fps question. For me 6fps with the option of 10 in a crop is sufficient - i'll be shooting a lot of wildlife. The D800 is a poor 4 fps; i'd have thought for the price it would have squeezed 5.5 at a minimum.
Loss of 1/2 stop of light? Well, maybe - we'll have to see for a real world test with production firmware. 24megs on a full frame sensor should improve things over, say, the A77.
Weight wise it's lighter than most other FF bodies. Battery consumption is poor, but hey, batteries are cheap (certainly cheaper than battery grips).
Plus i'll be shooting a good deal of video, and with the ability to adjust sound and use earphones, well that's great.
I'm yet to buy and will wait for the price to drop, but for me the A99 is a hot contender for my £ and am surprised that Canikon owners are not able to appreciate that this new offering from Sony has to be a contender for people looking to start from fresh or with older kit looking to update.