I find that the more I think about the film, the more I like it.
Alien, the film that occupies the same fictional universe as Prometheus, is, at it heart, a horror film that happens to take place in outer space (I'm oversimplifying a bit, but that's essentially true). Similarly, Blade Runner is a film noir that happens to take place in the future (again, oversimplifying).
Prometheus, on the other hand, is not a genre film with science-fiction trappings. It is most pointedly not a horror film (though, to be fair, it does have a few horrifying moments). Rather, it's a grand Science Fiction adventure in the tradition of Arthur C. Clarke and, surprisingly, Roger Zelazny.
It is a visually gorgeous film. I don't think there's any particular need to see it in 3D, but your mileage may vary.
The script is somewhat underbaked. Another pass or two at the script could have fixed the "people doing stupid things" problem that pops a couple of times.
Despite the problems with the script (which include the aforementioned as well as a blindingly obvious Chekov's Gun and some totally unnecessary foreshadowing of a big reveals), this is surprisingly thoughtful and multi-layered film that goes back to some of the themes that Scott dealt with in Blade Runner.
While it's clear that the title does refer to the Greek legend, I think that it also refers to another famous work of science fiction that similarly invoked the Prometheus legend.
Three stars out of four.