It is definitely good.

Rating: 9/10 (17 June 2012)

This film is an original story depicting elements that lead to Alien and Aliens.
I think movies are a lot about the emotions that the stories convey, and if you please bear with me, allow me to review this film and saga from the emotions that they created on me.
I first saw Alien as a child and was impressed by a raw horror & science fiction film, many years later one lonely night in front of my TV, I watched Aliens for the very first time and it was a real action roller-coaster based on the original Alien, although both movies center around Xenomorphs and a woman called Ripley they are quite different and equally enjoyable, both of them left me wanting for more.
Time brought Alien3 which I was quite eager to watch only to be severely disappointed and leaving me bored, then came Alien Resurrection which was a lot worse than the previous one, and made me feel even stupid for watching the movie, enough I said.
Years later we got Alien vs Predator and Alien vs Predator Requiem, both of which in my opinion are a total waste of resources and screen-time with no story whatsoever, only aliens massacring anything that moves for the sake of creating a blood bath. Please make it stop! Leave the Alien franchise alone I thought.
Now comes Prometheus which is the only film in the series not to feature "Alien" on the title (a good decision), just like Aliens to Alien this one is quite different to any of the previous films, it has a very good story,yet intentionally delivered in a raw way, I got many answers to the mysteries of the first Alien film, and I ended up with many new questions to answer and just like the original Alien & Aliens films, although it is quite different, I'm left wanting for more.
It is definitely good, and I would really like to watch a continuation of this story.
Saga rankings:
Prometheus: Good
Alien: Good
Aliens: Good
Alien3: Really Bad.
Alien Resurrection: Stupid & miserable.
Alien vs Predator: Stupid & miserable.
Alien vs Predator Requiem: Stupid & miserable.
The original elements created by H.R. Giger, Ridley Scott and James Cameron are quite good, after all the damage done to the franchise by the latter modern films in the saga, Prometheus had an almost insurmountable challenge of reviving the Alien franchise, and that is just what it did.