DxOmark just published the full Sony A7r sensor test. And according to their measuresand ranking system the camera scores the same points as the Nikon D800-D800E (and that for $500 less). And it literally kicks the Canon5DIII in the butt.
I have thousands of images from the D800 and from the 5D3, and there is no butt-kicking happening in either direction. While both do a fine job, for me and my work the disadvantages of the D800 outweigh the advantages.
DxO charts are interesting if you are just buying a sensor. But photographers evaluate photos and usability for their tasks more than sensor charts. The sensor is the least interesting thing about the A7/A7r, which looks to be a very interesting camera otherwise.
The (mostly) anonymous online complaints about Canon's sensors don't stop anyone from making absolutely awesome photos with Canon's sensors in a great variety of circumstances. This is proven day after day by thousands of photographers, including some of the best in the business. When I hear about or meet a photographer whose work I've admired for decades and their main camera today is the 5D3, that tells me a lot more than anonymous complaints on the Internet.