SONY A7r is a 36MP Full frame camera without low pass filter. The ”r” stands for resolution. In my experience the A7r is best suited for tripod use for serious studio work, architecture photography, landscapes and any other type of shooting where high resolution is called for or if you have a really steady hand - simply for everything except for sports and nature photography.
Most reviewers are quiet new to the EVF (Electric Viewfinder) and its possibilities for professional photography and almost all of them are present or former OVF (Optical Viewfinder) users.
Many mentions the low battery performance compared to the cameras with optical viewfinder, forgetting that the new technology needs more electric power to drive the LCD and the EVF - and give us all the important live information all the time. Since these reviews there was a firmware update which fixed most of the early problems so read these with a grain of salt - so to speak.
Downloadable Manuals and e-Books
Sony´s useful Help Guide
Sony A7, A7r Instruction manual
You can also buy Gary Friedman´s detailed e-books of the A7 and A7r
or Brian Smith's From Snapshots to Great Shots
Sony A7r reviews
CameraLabs detailed but early review (November 2013) with lots of videos and samples
Frank Doorhof´s Sony A7R review, Part one
Frank Doorhof´s Sony A7R review, Part two
Michael Reichman´s early hands-on review (October, 2013) Alpha and NEX Get Hitched
Dpreviews February 2014 Early thoughts on the Camera
Imaging resource´s review with update from april 2014
B&H PhotoVideo´s Guide for the Sony A7 Series Buyers Which Model Suits You Best?
Frank Doorhof´s comparing the RAW developer softwares in DxO vs. Capture One vs. Lightroom
A blogpost by Frank Doorhof FujiFilm vs Sony A7(r)
Michael Reichman – The World's Best Sensor Meets the World's Finest Lenses
Tips and tricks
Brian Smith: How to theter the Sony A7/A7r/A7s
Brian Smith: CAPTURE ONE adds Sony tethering support
Gary Friedman: Unobviuos Things about the Sony A7 and A7r
Gary Fong How To Configure Sony Autofocus (Moving Objects Or People)