I saw this movie by accident the first time, but have watched it 2 more times in the years since.
I would agree and strongly recommend to Sci-Fi fans but is an all round enjoyable movie.
Excellent effects and prop/sets, quite gritty, explored some new concepts and provokes thought.
Maybe it was a benefit to avoid any hype surrounding the film, but having watched it knowing nothing previous We found it very entertaining
Positives: Alien atmosphere and a nice kind of twist at the end.
Negatives: Not enough explanation about the Pandorum effect, confusing and not that intriguing.
So, overall, I'll recommend it to the other sci-fi geeks out there, provided you don't particularly mind having to chew on your popcorn a bit more than usual.