By sheer chance, the Sony rep was at the store today when I stopped in to buy "yet-another-G**D**-bag" ... I'll spare you my disgust with having to purchase another camera bag.
Sorry if I use the E-M1 as a basis of comparison ...
The Sony guy was there with the A7 (and I think the A7r but I didn't bother to hunt that one up after I played with the A7). It's small, it's light. The viewfinder is good (not quite as good as the E-M1, but quite good). The controls are, um, a bit simplistic and clumsy compared to the E-M1. The menus are Sony stuff, which is quite different from Oly stuff. With a 35mm lens on it, it handles ok. The A7 build feels good, not quite the superb tank like feel of the E-M1 but good enough ... I understand the A7r feels better and is more robustly built. The shutter is pretty loud (not quite an Nikon FM2 but close), the responsiveness is good if not up to the Oly standard. The body worked all right with the slightly larger zoom lens on it but I'd want a grip with it for larger, heavier lenses. No image stabilization in the body .. you get used to having that quickly and it is missed when gone.
Of course, I didn't have a Leica-R to Sony E mount adapter to try out my Summilux-R 50 on it, but my feeling is that one of these bodies with a Novoflex adapter would make a good replacement for a Leica R body, keeping the original format. I'd want the grip for anything longer than the 90mm for sure.
Overall, I'd say that aside from all the hubbub and stuff in the equipment forums, the A7 and A7r seem like a decent pair of cameras and a nice opportunity for those of us with high quality, orphaned SLR lenses.
Yet Another Fine Camera to consider if you have the money, time, and attention span. ;-)
G