First thing to say is: I'm a great Dead Space fan and I was really looking forward to this movie. I didn't watch any trailers beforehand to let it hit me with surprise like it happened with Downfall.
Since there is more than one summary of the story by now, I just start directly with my opinion.
Well, Aftermath DID hit me with surprise but I was really disappointed with the result. Althouth I was watching it in the dark with my headphones on, there was just no atmosphere, no tension building up. After the great and fitting art style they used for Downfall, I had hoped for something that would be on the same visual level at least. But the CGI style just didn't reach me and the different styles they used for the four stories didn't help to build up a steady atmosphere. For me, the first three quarters of the movie were downright boring. And the last quarter, with the fourth story be told and following the Necromorph outbreak on the O'Bannon, wasn't outstanding either. The inconsistencies already mentioned by previous reviewers were also a problem for me. Beginning with just the different designs of the space suits in the first two stories.
I really enjoyed the first movie, the first game and as well the second game so far, so of course I was pretty hyped for this movie which could be a reason for my disappointment. However, in my opinion even Dead Space fans should think twice if they want to buy this movie or if they prefer to give it a rent instead.