For a movie almost 3 hours long, the time went by quickly.
It is a standard story, wrapped in a SciFi blanket. Special effects well done, very much worth seeing.
Two things bothered me about the movie. First, the use of sound. It was probably about 90 minutes in to the movie before I heard any use of "located" sound (ie, coming from a distinct speaker to try to place you in to the scene) and when I did hear it I thought someone was leaving from an upper door and let it slam.
Secondly was the dichotomy of biology. It seems as if every creature on the planet has 4 forelimbs *except* the dominant species. It just seemed a bit jarring to me.
The story line is pretty predictable, but it is wrapped in a very nice wrapper.