I'm sorry Sony, but I can't stop laughing at the painful looks of the camera bodies you've mangled.
You took a very handsome, curved block that looked almost exactly like a Nikon 1 (not a good idea, considering what Nikon are telling Sakar/Polaroid with the lawsuit), plopped a viewfinder onto it, and riveted a grip onto it.
It looks home-made, like someone's $100 camera body mockup. Frankenstein's creature was possibly less ugly.
Now, technically, it sounds interesting, but they need to show how huge the lenses are, especially the long lenses, mirror-less or not, it's still 135 format. Trying to get a good day's work out of it is going to be heavy.
DPReview seemed incredibly supportive of Sony in their first look assessment. The controls are there but seem illogically placed, as if the outer form followed the inner form, as if the design came from an electronics company. Samsung and, to a lesser extent, Panasonic have been doing similar types of design work, but Panasonic finally got it right with their GH3, save the SD Card door and Display button.
Supposedly, the grip on the a7 and a7R is quite good, so it should be comfortable.
The lens selection looked a bit bizarre, and given their lack of lenses for their NEX line after these (3, 4, 5?) years, will they improve in their variety?
The features of the two bodies was interesting. Choose the less expensive body and get a lower resolution (logical) sensor with a anti-aliasing/low pass filter or pay quite a bit to get a higher resolution sensor without the filter. Of course, if you can afford the more expensive model, they're thinking that you already know how to handle moiré patterns.
Still, I can't see the more expensive model going up against the Nikon D800E or any medium format camera. I also couldn't see the D800E going up against medium format, although the resolution is plentiful. Have I thought about buying one? Definitely, and I've thought about the D800.
Are there people out there who chant "full frame full frame" as the universal panacea? Yes! Could this fix their desire? Possibly. However, I feel that those people will still have trouble getting the photos they want because they may never know their equipment, and could do much better with the equipment they have, until they've explored everything that a camera body can do.
Update 2013.11.05: Well, that didn't take long. Nikon's new Df matches 1970s style with 2013 specifications and even allows lenses from as far back as 1959. That's a lot of crossing time, and you don't even have to switch equipment brands. The main difference for people trying to decide is whether they want better image quality or higher image density, since the Df uses a 16 MP sensor from the D4. Of course, thinking about ISO 25,600 photos as clean as most ISO 1600 photos has appeal. If you happen to photograph concerts for a living, you have a new backup camera body in the Df or your company could afford a couple of them instead of one D4.
Update 2013.12.10: The a7/a7R duo have had mixed reviews. They have a lot of potential but they're products of checklist engineering. I think they'll be useful to the casual photographer. I somehow doubt that a professional would consider them, but a few professionals have considered micro Four-Thirds, so why not this pair and the Sony FE-mount? Any camera body currently available is good, and these have to be far about just good.
Update 2014.12.18: While I'm still not a fan of their electronics-oriented designs, Sony has gone further with these and produced a successor to the a7 and added the a7S with ISO sensitivity up to 409,600 and increased dynamic range. The sensor has 12 MP, which should provide good enlargements with lower noise than most, given the low pixel density.
The a7 II has 5 axis image stabilization, similar to what Olympus started with the OM-D E-M5. This should improve quite a few blurry photos.
The company has come a long way from buying the assets of poor Minolta.
Update 2014.04.08: I'm glad they've revised the body greatly with the A7 Mk II. It seems much better overall.