I saw the movie on tuesday night. I'm a huge alien fan, and had been hotly anticipating this movie for years.
I was quite pleased on the whole. It ended up being more of an extended character exploration than anything else. But it was a horrifying and fascinating character, so I had no real objection on that front. My biggest issues were with the writing for a particularly clunky character, and the final "action" sequence of the film. That last action sequence just seemed very pandering and extraneous. It could have been cut out of the movie entirely without really losing anything.
I'm very much looking forward to getting my hands on the home video release, but I'm also a little worried that the Blu-ray isn't going to include a directors cut of the film. Ridley Scott's films frequently benefit from getting directors cuts, they are notorious for getting cut down significantly for wide release. I suspect that some of his more recent films haven't gotten any of that due to the amount of post-process work that has to be done. The studio is less likely to spend the extra money to finish shots that aren't going to be in the released film.