I watched it tonight. Thought it was ok. Nothing all that special, really. I think the real weakness in this is the need to connect it with Alien at all. The film would, I think, have been more enjoyable if it was a completely standalone product. No references to Weyland, no Engineer-Space-Jockeys, no biomechanical creepy-crawlies. But then it'd just end up being Mission to Mars or First Spaceship on Venus or any number of other films.
The thematic stuff...eh. It's ok. Nice try, but I think the execution was hampered by the need to delve into the Alien connection and create another "spam in a can" scenario.
I guess my take on it was that it wasn't BAD really (certainly not as bad as Mission to Mars), but it had some bad elements that hamstrung it, other elements that hamstrung it in a different way, and what was left ended up being a little...I dunno...uninteresting.
Part of the issue with the lack of characterization (and bad characterization in some instances) was that I really didn't give a crap about anyone in the film except...uh...whatshername. The Ripley stand-in.
I had similar problems with Alien 3, actually, when half the cast is there just to get killed in a variety of ways. That, in my opinion, is a hallmark of crappy horror films which, while entertaining, are hardly what I'd call a thinking person's film. I felt the same connection with the bulk of these characters as I do with the average character in a Friday the 13th film. That could have been dealt with differently if the characters hadn't been portrayed as they were, or if their behavior was a bit less "DON'T GO IN THERE" stupid.
Meanwhile, somewhat more interesting themes of discovery and faith end up lost in the shuffle to the point where, yeah, I saw them...I just didn't really care. I mean, I had my own questions (the obvious stuff like "Why create, only to destroy?" and "So, who the hell are they bombing anyway?"), but let me put it this way:
If not further Prometheus films were made, would I feel ripped off due to the unanswered questions? Nope. Not really. It might be interesting to see, but I have a hunch the answers won't really satisfy.
On the whole, I give this film a solid "meh."