dpreview has posted a first impressions review of Sony a7RII (Amazon, B&H Photo Video, Adorama). Also add some high ISO images of Sony a7RII, here is a quick high ISO comparison with Nikon D810, Canon EOS 5Ds R and Sony a7S.
Sony a7RII Vs. Nikon D810 at ISO 51200
Sony a7RII Vs. Canon EOS 5Ds R at ISO 12800
Sony a7RII Vs. Sony a7S at ISO 102400