If you are interested in the Alien franchise, then read the novel. It's a bit different than the movie; leaving things out, adding things in. The novel gets into Jones the cat's head, which is funny. The alien is barely described, however.
We get to see the crew interact and understand their motives. There is a lot of time spent on this and does slow things down, but as an Alien fan, I found this book a good read nonetheless.
Check it out.