Alien Covenant is a monster movie that takes place primarily on a terrestrial planet, but there are a few scenes on the space ship. It still felt very much like the previous Alien films. There were multiple times when I leaned forward in my seat in anticipation and many more where I shrieked back or jumped up in fear. It had a psychological angle to it which kept me engaged, and prevented me from "checking out" and screaming at the monsters.
My favorite thing about this franchise is the female protagonist. Katherine Waterston of Fantastic Beast fame fell nicely into the role. Michael Fassbender playing dual roles of David and Walter was also fun to watch. He was creepy, but entertaining in both roles. The rest of the crew were delightful as well with the exception of Oram played by Billy Crudup. I struggled to come to like him in the film. His character was supposed to be different from the others because he was a man of faith, but he just came across as a victim of an unseen persecution. I think the film's intent was to get the audience to think about the contradictions and correlations of science and creation. Instead of it being a deeper layer to the film, it just felt like there was a fly buzzing in the room keeping me from enjoying the action.
I would recommend that you see the movie in the theater if you enjoyed Prometheus. The special effects were well done and I love to watch a horror movie in the theater because the reaction of the other audience members adds to the fun. This is the kind of movie where people react audibly so if that bugs you, you may want to wait.
Most of what you saw in the previews does not show up in the film. Some people are grateful for the extra scenes but most view that as false advertising. I think they were presenting the previews as a way to get to know the characters before the opening scene. I don’t think that the previews were misleading just that they contained scenes not in the film. This is a pet peeve of mine, so I thought I would mention it.