Not sure what Carrot is talking about in terms potentially not being able to follow it: I've only seen the Alien films about once each, and not seen any build up to this, and it was fine really. I recognised the ship and the navigator/engineer and all that stuff, but then maybe I've missed a load of stuff that I don't realise, but I wouldn't mind that - stuff you only pick up on after a couple of viewings is sadly lacking in movies these days.
The movie itself is pretty solid (and some folks will know I'm a pretty hard-to-please critic of current movies

). However, I do wish Hollywood would stop actively
telling you the plot with laboured exposition and
show it to you more. There's a lot of pseudo-philosophical one-liners and rambling about meeting your maker that just clogs up the film and makes the characters much less believable in my opinion - they're shiteing on about the reason for their creation when they should be either speechless or saying "holy fuck, aliens!!!"
Along those lines too, is the need to literally show everything clearly - in the original you only see the only a couple times before the end, and so it's terrifying. Nowadays everything is shown really clearly and this actually detracts from a film - often less is more, and though it leaves you tantalized that feeds the imagination more and is better in the long run.
The abortion is indeed a very weak link as mentioned by someone else - the scene itself, yeah, ok fine, whatever, but the fact that no-one bats an eyelid about it is just crazy - "woah, what the fuck happened to you? how come you're in your underwear and covered with blood?" Even David doesn't mention it like "hey, what the fuck did you do with our specimen?" Everyone is just like "Heya, shaw, you coming back to the pyramid/dome with us?" Not to mention running around after a caesarian is pretty fucking silly, but whatever on that bit.
However, I think both the biggest weakness and strength is David - his character is totally nailed by Fassbender and he treads a really great line between total dude and total bastard the whole time. The bad part though is that David-bit just figures way too much stuff out (or seems to) and is responsible for moving the plot on far too much for one character - he triggers the holo-video, he finds the acid goo, he takes a pod back, he deliberately spikes a drink (ostensibly unaware of what will happen, but he seems totally prepared for the results), he's totally unsurprised that she's hosting an alien in her, he can fly the ship, read the language,
speak the language (though they do try to explain those two). It's not that those events should never have happened, I just think it could've been done slightly more plausibly with a bit less reliance on his unreadable motivations/understanding.
Odd question: why were all the maps on Earth pointing to this planet? "Go here and destroy yourself"? That made sense if it was the homeworld, but less sense as a death world - "I know, let's make a death planet, then we'll go to Earth and tell them to find us there, and when they have space travel they'll go and die!! Woot!" Sure, they did try to go themselves it would seem, but then, clearly they made it there as well, otherwise no carvings right? Hmm, have to see how that one pans out.
Overall though: good action/alien movie. Not really scary/horror enough, but a decent amount of scares/tension I reckon, and good gross-out money-shots. Theron was good, Fassbender was great, Rapace was good, ship crew were a bit weak. 3D was good, colour palette and design great (I loved the fact that it wasn't Alien Adventures in Space with loads of planet hopping or anything bloody ridiculous like that, it was just in one place). Dialogue a bit baggy and tired in places (as mentioned, less would've been more) but overall, yeah, thumbs up. Not a full thumbs up, pants down, but a big thumbs up. The most enjoyable movie I've seen in the cinema in a long while.