It's thought-provoking, unique, exciting, and one of the best science-fiction movies of the 21st century so far, as well as one movie that demonstrated how 2009 was an unusually good year for the sci-fi genre as a whole.
It's also packed with social commentary regarding race and how refugees are mistreated in real life, considering in this movie, it's the aliens who find themselves in the middle of a large-scale refugee crisis. It's thought-provoking, unique, exciting, and one of the best science-fiction movies of the 21st century so far, as well as one movie that demonstrated how 2009 was an unusually good year for the sci-fi genre as a whole.