This is based on watching the movie once, and directly after doing so.
The overall topic of the movie is quite incredible, in my opinion, but the execution of the film and other points I'll mention brought it down for me.
First off, the crew of the film was very small. Obviously, there were quite a few actors that got appropriate screen time, but the full credits only last for about 30-45 seconds.
Secondly, there are a few moments where the film has confused me, such as the atomic bombs going off, how CJ Tomason's character seems to just completely ignore pain at multiple points, a few small details that struck my attention, and the end of the film.
Third, and what will be my last point, is the development for the characters. There really was none.
There is, however, something I found interesting and that deserves some notice. The makeup artists did a great job on most effects. There were points where you could tell it was fake, but the rest seemed spotless to me. The music is also pretty good, so thumbs up there as well.
Bottom line, Aftermath is, what I would say, a film doesn't completely work correctly. It's not the worst movie you'll ever see, but it surely won't be the best. To me, there's ups and downs. It tries to have this horror element to it, but fails to do so. Action, pretty good.
Truth be told, I got to have a little fun while watching this by calling events before they happen. I got a little laugh out of it.