Since no one has mentioned it here yet, mirror ghosting - deal breaker or non-issue?
It's mentioned on other review sites with samples. The mirror, with its two surfaces, can result in an offset secondary ghost image superimposed on top of the main image. This is particularly visible in night shots where there are bright small sources. I counted the offset to be about 12 pixels. Assuming the mirror is 30% and 1% reflective on its two surfaces would mean the ghost would be a bit more than 7EV down from the original, but might be better depending on the quality of the anti-reflection coating. Another site estimates it at 8EV in practice. It isn't limited to night shots though, and can appear anywhere you have a very dark area next to a very bright area.
_________________Canon DSLRs: 7D2, 7D1, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 10-18, 15-85
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 50/1.4A, 150 macro, 120-300 f/2.8 OS
Compacts: Sony HX9V, Fuji X100.