Warning: There might be some potential spoilers in this review.
Even though my expectations weren't grand, I still found them... out of place. The best comparison I think I can make is to say that this was less like Ridley Scott's Alien and more like Danny Boyle's Sunshine. The story itself is a slow burn that keeps its focus on philosophical ideas... and then pops in a "monster" in the third act. And all of this is equally the best and worst thing about the film.
The philosophical ideas and the themes delivered for the origin of man were explored rather well. Without getting into too much spoiler territory, I like how this both explained the origins of man, as well as the origins of the Xenomorphs of the original series. (But I'll warn you now--those going in expecting another addition to that franchise and/or formula will be saddened. This works as a kind of origin story, but you won't find any alien carnage.)
And I suppose that's where the film is a kind of let down. Not that it doesn't have that, but that it doesn't have... well... anything. The movie is over two hours long, and there's maybe 10 minutes of action or suspense in the entire film. The film acts like a slow burn that leads up to very little. A 15-second payoff before the closing credits. I wouldn't say the movie is overly boring or anything. It just takes its time exploring the aforementioned themes, but it never feels like the payoff is equal to the buildup.
So while the film is a good one, and the visual effects are outstanding and gorgeous, I guess I was expecting a little more. And this coming from somebody who wasn't overly expecting a hell of a whole lot to begin with, I can certainly understand why a lot of people have come out of this disappointed. The story is good. The acting is great. The action we do get is really good. But I just found some structural flaws and a few off character decisions that didn't gel well. In other words, what it did well, it did great. But as a whole, I wanted a little more.
I Am McLovin!
(P.S. Why age-up Guy Pearce and not just get an older actor? Was the only reason they got Pearce so that he could do the promotional viral video a while back? And they wanted to keep continuity between the two? That's the best explanation I can think of.)