I'm using the A7R as a sort of "place holder" until Canon delivers a body with a sensor that satisfies me.
I have really liked the performance of the A7R sensor.
I have not had issues with the shutter vibration or light leaks – although I certainly acknowledge that the issues are real for some under certain situations (however I struggle to find a practical set of conditions under which the light leak would pose a problem).
I am not enamored with the Sony's ergonomics and control layout. It could largely be because of my years of time spend with the EOS system however to me the Sony's feels more like it was just "built" rather than having "evolved" as the Canon DSLRs have... if that makes any sense.
In any case the A7R is a nice small body with excellent image quality that performs as well or better with my Canon EF lenses than do the 5D Mark II or 6D.