If anyone hasn't read the short story that Arrival is based on, definitely check it out, it's called "Story of Your Life". Ted Chiang is a fantastic SciFi writer and I was very excited (worried?) that this particular story was chosen for a film adaption, as it doesn't seem to lend itself well to the medium. But based on early feedback I'm optimistic.
Not sure how closely the movie follows the short story's plot, but obviously spoilers could be involved, so fair warning. Here is a PDF version of the story: http://cfile203.uf.daum.net/attach/254E884754DC52CB277F4F