This could go one of two ways, and I won't know which until I get into it. Essentially it'll either end up being vaguely complimentary with a few qualifications, or a bit ranty about unfulfilled promise. Either way there'll be spoilers I'm afraid - let's dive in. Prometheus is the much-vaunted return to sci-fi by Ridley Scott, and also a semi-prequel to Alien, being set about 30 years earlier. After finding a series of ancient paintings from otherwise-unconnected civilisations all depicting the same star system, and showing people seemingly worshipping extraterrestrial beings, a mission is despatched to investigate, and hopefully meet them, working on the maybe-a-stretch-but-sort-of-reasonable assumption that they may have something to do with the origin of humanity.
Arriving at their destination after a couple of years' travelling, we meet the crew mostly in passing (who have been in stasis, with the exception of android David (Michael Fassbender), who spends his time pottering about, watching movies and learning languages), including icy boss Charlize Theron who's funding the mission, laid-back pilot Idris Elba, religiously-leaning explorer Noomi Rapace, and to be honest pretty much everyone else has got cannon fodder written all over them.
Landing on the planet and finding a structure, they explore and eventually find not only the long-dead bodies of the previous inhabitants, large humanoids in spacesuits, but also a cavern full of containers, which seem to start reacting to the explorers' presence, bubbling slightly. Two of the crew find it all too much and head back to the ship, while the others retrieve the severed head of one of the aliens. Meanwhile David seems to be on a separate mission the others aren't aware of, securing one of the vessels (a suspicious android in an Alien movie? Surely not). Upon their return to the ship, David clearly has plans for what he's recovered, the two scientists haven't returned, and both events lead to nastiness.
The trouble is, while seeing it all unfold is interesting to watch, increasingly questions are raised which aren't answered or even remotely dealt with. And not in an intriguing "let the audience discuss it afterwards" way, more just in a "meh, let's just crack on and hope no-one notices" way. It's made clear early on that we're a product of the alien race, and equally clear that they now intend to send a load of biological warfare our way, and while someone does briefly ask why, it's just left floating - nothing to suggest, in fact, that both sets of events aren't solely to advance the plot.
There's also no real reason for Charlize Theron's character to be on the ship - excise her from the plot, and everything could happen almost exactly as it does. Her motivations for being there are tenuously explained, but don't really help much. The main control centre on the ship has a 3D projected display of the structure with the crew's positions marked in it, together with the mapping probes. Looks very pretty, but as far as I can recall no-one ever really interacts or refers to it, and the cynic in me wonders if it was added independently from the script. Despite having everyone clearly shown on it, when the two scientists who break away from the main party don't come back, people seem surprised, rather than noticing the two yellow blobs still left near the cavern. Likewise we then find out they've got lost in the structure, rather than using any of their high-tech mapping equipment to navigate. Oh, and they deliberately move away from a reported life sign, ending up back in the cavern, where they discover a reptilian creature and POKE IT! Which of course goes badly wrong for them both.
I didn't mean this to turn into a mistake-spotting session, but it's clearly ended up on the more ranting end of the scale. My point is that there are quite a few of these little issues which crop up - not plot holes as such, but unexplained questions which detract from the finished product. When everyone just seems to do what's demanded by the plot, rather than following believable lines of behaviour, I find it very hard not to get detached. Michael Fassbender's David is an exception - you're never quite sure where he stands, but in a way that seems deliberately constructed, not just as a byproduct of lazy writing. There are hints of self-determination, but also a strong implication he's under direct orders, and more characterisation along those lines would have helped a lot.
This is sounding more negative than I feel - despite my numerous reservations, it's still an entertaining watch, and at times visually spectacular, I just wish the story and characters were more filled out. Alien was tense and contained, with a single faintly mysterious threat. Aliens was more gung ho with broader character strokes, but still very effective on its own terms. Prometheus fits uneasily between the two - a large scale idea without enough small scale interest to really do it justice. By the end, we're not much better informed than we were at the start - it ends with potential for a sequel, but like the rest of the movie there's no real sense where it might go, just the implcation that something could happen, without really getting a handle on what that should be.