If Ω's ridiculously paralytic review of the Sony A7r wasn't your thing, how about checking out About Photography's review by Tom Grill? It is concise and backed with performance comparisons with the Leica 240M.

Tom believes the A7r isn't ready to replace your digital Leica system. He concludes that we must wait until Sony have brought to market comparable Zeiss lenses. Then and only then will the A7r show its mettle.

“My main purpose in this experiment was to determine if the A7r could serve as a higher resolution substitute, or act as an extra body for a Lecia M system. In the end I concluded that the results, while marginally better from the higher res sensor, were not enough for me to use this camera instead of my Leica M 240. The Leica worked better and with considerably less post-processing hassle using its native lenses. This tended to negate any benefits the larger 36MP A7r sensor might have. If it’s a less expensive spare body I want, I think I would opt for the features of the A7 over the A7r and save even more.”

You can find it here.