Here are the first 4K UHD BR disc reviews that I have seen. They are both from Fox:
The Martian
Exodus: Gods and Kings
http://www.blu-ray.com/movies/The-Martian-4K-Blu-ray/147430/#Review
http://www.blu-ray.com/movies/Exodus-Gods-and-Kings-4K-Blu-ray/145678/#Review
John
The Martian
Exodus: Gods and Kings
http://www.blu-ray.com/movies/The-Martian-4K-Blu-ray/147430/#Review
http://www.blu-ray.com/movies/Exodus-Gods-and-Kings-4K-Blu-ray/145678/#Review
John