It's a weird jumble, in some ways almost completely meaningless and contradictory. Basically, a number of good scenes threaded together with not much logic. Lowlights include the two scientists trying to make friends with cobra-willy (it's not friendly, and the clue's in the name), the blonde lady doing quite a good impersonation of Helga from 'Allo, 'Allo, and the sheer lack of sense of some of it. It confirms my suspicion that Ridley Scott makes some of his films with the volume turned down.
But - this is a big but (and I cannot lie) - it at least tried to do something different. It was at least an attempt at something other than Space Monsters vs The Marines which we see over and over again, each time more woodenly and stupidly portrayed than the last. It actually did make me think. I didn't think very much, and I didn't conclude that it was a brilliant film, but in the land of the total idiot, the half-brained man is king. That's probably as much a reflection on the poor state of things than any particular greatness in this film.