This video shows Mark Kermode reviewing Prometheus. He discusses the movie with Simon Mayo in detail, also venturing into the whole science fiction genre.
The mistake a lot of people appear to be making when they head into see Prometheus is expecting a straightforward, direct prequel to Alien. But this is not, and was never meant to be, that.
As Kermode points out in his review, Scott has treated Prometheus as more of a chance to explore the themes which led to both Alien and Blade Runner, and there are at least two films-worth of storyline between Prometheus and Alien.
Just watch Prometheus with an open mind and enjoy it for what it is. Otherwise you may end up being really disappointed.