If you liked this movie then check out...
First off, I just watched this yesterday and I LOVED it. I went into it with an open mind, not knowing what it was about except that it had a horror aspect to it. I suppose I was expecting something like Alien but I was pleasantly surprised that it was actually quite different (don't get me wrong, I love Alien). Loved the twist with the "aliens", as well as the end. For me a good movie is one that goes beyond instant entertainment and makes you think about it afterward.
As a fan of the Sci-Fi genre (and a big fan of the "stuck on a big space ship/station" genre), I thought I'd list some other movies that you might enjoy if you liked this one as much as I did. Top ones are my favorites.
Sunshine (2007)
The Fountain (2006)
Serenity (2005) - but watch all of Firefly first!
Moon (2009)
The Thing (1982)
Event Horizon (1997)
The Abyss (1989)
Alien (1979)
2001: A Space Odyssey (1968)
The Thing (2011)
Solaris (2002)
Mission to Mars (2000)
And a couple TV shows:
Battlestar Galactica
Stargate Universe - This is sure to piss off a lot of the SG:1 and SG:A fanboys as it went in a very different direction, but from purely a "stuck on a big ship" standpoint, I think this show was spectacular. I was pretty disappointed when it got cancelled after the 2nd season.