Interesting to see above that some of you were on the South Bank on Sunday. I was there as well, with 4 friendly dancers that I help out with some nice photos from time to time. I saw so many people with big DSLRs but nobody with an A7/R. Maybe they were too small to see! Here's a quick selection, all with the A7R.
The full set is here if you're interested (there's one RX1 shot in there).
I used a mixture of the Leica 50 f/2.5 M Summarit which is just sensationally gob-smackingly sharp, the Olympus OM 21 f/3.5 which is also very crisp and sharp and smear-free, and a Konica M-Hexanon 90 f/2.8 which is very sharp though it does benefit from a slight contrast boost in post processing.
The lit shots were done using one or two flashes and a shoot-through umbrella triggered by Pocket Wizards. I've got one of those 3-flash mounting brackets to can slot 3 lights onto one stand. Usually I trigger one with a PW and the others ping on optical slave mode. The A7R was on 1/160th I think to ensure flash sync worked OK. The one shot where I needed a flash sync speed was done with the RX1 at 1/1000th.
Oly 21mm
Leica 50 2.5
Leica 50 2.5
Leica 50 2.5
Oly 21
I did have the same problem with the viewfinder in strong sunlight with the sun 90 degrees to the right of me. I wear glasses as well so the sunlight shines in the side of my glasses. Same thing happens with other cameras I have but it does make manual focus tricky. I ended up just shading that side of the camera with the hand I hold the camera with and it was OK.
Overall the image quality from the A7R is pretty gob-smacking. Zoomed into 100%, some of the portraits with the Leica 50mm lens are almost surgically sharp, showing up every pore, tiny flakes of skin etc etc.