BBC cameraman Johnni Behiri posted his A7s review at Cinema5D (video on top). He writes:
The direct competitor to this camera is naturally the Canon 5D Mark III. Personally, I think it is time to move on and say goodbye to the Mark III. You now have an amazingly sharp looking video camera that records in a new robust codec (XAVC S), very small with a build in great OLED EVF and last but not least, also a lowlight king. I also have to had that the audio recorded directly to the A7s is much better then the one recorded on the Mark III because of better internal preamps. All in all, if you are looking for a working tool that is small enough to look “un-professional” yet one that records great looking video footage at a price which is not modest but affordable, look no further. The Sony A7s is your best friend.
Steve Huff also posted his full A7s review and writes:
For me, this is the camera to beat for 2014. So far, my pick for camera of the year. For me, if I add in the Voigtlander 15, Voigtlander 35 1.2 and the Sony 55 1.8 and I have a camera and lens combo that can do just about anything I ask of it, for my needs.