Without giving too much away about the movie, the thing that struck me the most was how at first you are frightened by these aliens. They are ugly and they seem quite dangerous. As the movie progresses though you begin to sympathize with them and even like them. You also start to see humans as the villain.
Sadly, it is not hard to imagine this being the way humans would react in a situation where aliens are stranded on our planet for a long period of time. Governments would want to do experiments and try to steal as much of their tech as possible, while people would fear and try to keep them contained.
I highly recommend seeing the film. In fact, I might try and see it again.