I loved the visuals in this, and Amy does a great job of carrying the cast. I am able to suspend my disbelief for 120 minutes when watching sci fi, so I will avoid the useless "but that's not what the military would do" comments.
The movie has a great setup talking about language, culture, our perception of the world and how truly -alien- an alien life form would feel to us.
Unfortunately, it uses that setup to deliver a platitude older than written language and then just throws away any conclusion to its sci fi story that we though was the main focus up until that point.