It appears that I am going to disagree with a fair number of people when I say that I quite liked this movie. Sure, if you expect some deep story with a lot of moral cleverness in it you are going to be disappointed. This is an interesting story but one that hangs together by a fairly fine thread.
To me it is a decent enough story that is propelled by a decent enough action and absolutely wonderful scenery. Yes, I agree with everyone saying that it is a bit of a B-story. It has many issues and barely hangs together at times.
However, if you try to ignore that for a while and just try to view it as a piece of, fairly fast paced, visual entertainment, well then it hits the spot quite well. It is frequently beautiful to watch. The action sequences are not bad and the story is, if nothing else, certainly not the usual thirteen to a dozen B-movie repeats. The acting is, well, also generally of B-movie quality but it is not downright bad and, once I got in the right mindset for the movie, it did not disturb me.
On the whole I quite liked this movie but I guess you have to be a bit of sci-fi fan, with an emphasize on visuals, to do so.