Check out the above Sony A7R II hands-on video that covers some of the key highs and lows. It’s a long video but some good info in there. Midway through the video, you get some direct comparisons to the Canon 5Ds R as well.
Sony A7R II Hands-On
[youtube https://www.youtube.com/watch?v=6yottoM_P1o&w=700]