Remember the time when animation used to be for kids? The good ol' days, eh? This animated movie makes pretty good use of the medium to tell a rather complex story. The movie has most qualities of good storytelling - ethical dilemmas, unique settings and gray areas aplenty. The premise of the movie is simple: Threatened with extinction, the human race needs to make one last desperate attempt at survival by the conquest of a seemingly peaceful alien world teeming with sentient life.
The movie explores possibilities that are the antithesis of staple sci-fi genre. For instance, What if the (typical) victim is the aggressor? (Humans attack a seemingly peaceful alien planet). Is peaceful bliss really a practical possibility? (without advanced weaponry, the alien world is threatened with extinction). Another highlight of the movie was that the aliens were, you know, just alien. They weren't cute and cuddly (a la E.T.) or menacing hordes (a la every-sci-fi war movie you've seen). The aliens are just rational beings who will fight, feel and cry when the need arises.
Now, the movie isn't without its flaws. It's not completely balanced (aggressors - no matter what the reason for aggression - are still painted in a slightly negative tone), characterization, even the quality of animation (in this post-Pixar universe) might be called into question - but I'm willing to overlook all of that for one simple reason: the director has a clear vision and explores it vividly on screen. That's worth a couple of hours of your life. Definitely is.