Were expectations unreasonably high? Probably. Alien came out near the end of a period of experimentation and boundary pushing in American films. It's relentless nihilism, it's bleak view of space, humanity, and the future was a reflection of the world the film was was created in. While technology has advanced, mankind has not changed, with the main motivations being greed, mistrust and fear. After the trauma of the Vietnam war, the civil rights movement (and it's exposing of the dark underbelly of America), political scandals galore and a general feeling of social exhaustion, the future of ignorance and terror conjured up by Ridley Scott, HR Geiger, Dan O'Bannon and the rest of the creative team seemed to be a perfect fit. The sequels carried forward these themes, while also reflecting the times they were made.
Unfortunately, Prometheus is a pale imitation of the first three films (and only surpasses the fourth, due to Prometheus looking better). The main themes - where did we come from and what is existence about - could have been interesting and the genre is a good venue for examining weighty issues. However, they are handled so poorly and never addressed in a thoughtful way, that little of interest is said about them. All that's left is the nihilism and a vague discomfort with technology - as well as the always popular mistrust of corporations.
Set less than 100 years in the future, the film deals with a corporate expedition to distant world (LV223...not the planet featured in Alien and Aliens for those keeping track). The ship's crew is made up of a mix of scientists and the rougher "working class" spacemen popularized in the first film. The purpose of the trip: to meet an alien race that visited Earth over the course of thousands of years...and may be responsible for the creation of life on Earth over a billion years ago. Of course, what they find on LV223 is less than friendly.
Even with little thematic core, a film can still be entertaining. Here too, Prometheus fails. While it has a capable cast, they have little to work with in terms of dialogue or characterization. The motives of the protagonists are poorly developed, and, at times, incomprehensible. For example, the protagonist - Elizabeth Shaw played by Noomi Rapace) believes that mankind was created by whatever they will find on LV223. Why? There is never any evidence of this presented prior to the characters arriving on the planet and Shaw never really explains how she came to this conclusion, other than she has faith. The problem; because Shaw never explains what led her to this conclusion, no matter how cursory the evidence, her faith - and primary motivation - has no basis and is meaningless. If the point were a negative commentary on faith (basically, that faith in any creator is wholly irrational), then the lack of a rational might be acceptable. However, the character's faith is later rewarded, in that she finds evidence supporting her beliefs. So, then blind faith is good? Even if this is the message, which I doubt given the outcome of humanity meeting it's maker (it's not happy), the problem of basic motivation of characters is widespread.
The supporting characters are worse; calling them one dimensional would be giving the screenwriter too much credit. They are a collection of tics and plot devices. Characters do stupid things to advance the plot. A perfect example: the team biologist, upon seeing a slimy, snake-like alien with a nasty looking mouth...repeatedly pokes his finger at at it, under the notion (delusion?) that it's friendly. Of course, nothing good comes of this. It is such a transparent plot device - an action scene is needed and cannon-fodder characters need to die - that it is, quite frankly, insulting to any audience member who is more advanced than a drooling moron. It is particularly noteworthy because the same character, discovering the body of an alien - something you assume most biologists would be eager to examine - begs off, saying he doesn't like bodies and wants to go back to the ship. So, dead body is scarey, living alien snake monster...is just like a puppy. Such moments are common.
In the end, you have a solid cast, a proven director, a huge budget, a great team of effects artists, all at the service of a terrible script. Ultimately, the blame has to lie with Scott and the producers. The screenplay is so laughably bad that there is no excuse for them reading it and saying, "yeah, let's shoot this." If this were some no budget, no name, shot in ten days, SciFi (sorry, SyFy) Channel exercise in tedium, it would be excusable. Given all the talent and resources this film had, no such excuse can be made. At some point, the pretty pictures have to be in the service of a story worth following. Otherwise, what's the point?
