My theory: It's the studio's fault

Rating: 6/10 (3 June 2012)

Don't compare it with the first two Alien movies and you might enjoy it!
Prometheus for me is the most disappointing movie in history. Maybe it's because of the buzz, trailers and overall marketing campaign being so intense and promising that basically no movie in the end could live up to that.
BUT: I believe that Scott's original cut was at least 30 minutes longer. Some scenes from the trailers & teasers were not in the final cut (f.e. "you're smiling", and when Shaw stands in front of the mirror folding her hands to pray (a very powerful scene by the way), the powerful speech of Weyland (and this is the only reason why they haven't cast an old actor for the role...and Guy had to go through all the make- up torture). And this might just be the tip of the iceberg. It explains why there are so many plot holes and the film seems so rushed. There is basically no build-up of suspense, it feels rather like a plain "ticking off" project milestones. I would even go as far as to say that the movie has no soul - something that made the first two Alien movies so magnificent.
So basically with a big budget movie at hand I guess the studio's options were either an R rating with not more than 2h running time, or PG-13 with 150-180 minutes (like Avatar). Unfortunately they decided to go for the first option. And as far as the R rating is concerned: there are not more than two or three scenes in the movie that justified an R. The movie could have been easily toned down to PG-13 without losing a lot of intensity.
This all being said, it's still a decent and entertaining movie, the look and the cinematography are superb. Just don't expect anything near the first two Alien movies.