I enjoyed the movie but in saying that I'm sure there will be those who will dislike it. I had heard that PROMETHEUS was going to be an ALIEN prequel and then I read articles by the filmmakers saying that it wasn't quite that. I think if your expectation is to see a movie like any of the previously released ALIEN movies, you'll be disappointed.
It's definitely the kind of movie that you walk away with having to digest what you just saw. Many of the movies today give scripted plots: Danger, Action, Love Interest, Action, Convenient Ending Where Everyone Survives. This movie gives the danger and action but leaves you wanting to understand more about this world, about the Engineers and about ourselves.
While it does answer origins of the aliens, the filmmakers did not clearly lay out *how* the science behind the aliens works. And that was the case with most of the revelations in this movie - it left you unanswered questions. And to some degree I'm ok with that. For me, it wasn't a frustrating feeling of "Dammit that was a cruel cliffhanger!!!". It was more of an fascination of "what ifs" and "may be it meant this".
When it comes down to it, I think the determining factor of whether one likes this movie or not will be based on the expectations going in. If you wanted a straight horror/creature feature, you'll be disappointed. But I simply loved this film for the mere fact that I walked away having an amazing discussion with my hubbie about science, religion, expectations, curiosity, greed and fish bowls. Yes, fish bowls! It's been a long time since a movie brought that much intelligent discussion and for that, I LOVED IT.