I saw it on Friday night. I was actually really surprised how empty the theater was. We saw it in 3D at 8:30pm on opening night, but it was like going to see a movie that's been out three weeks on a Sunday early afternoon. Then again, the IMAX theater was right across and had an overlapping showing.
Regarding the movie itself, I agree with Pyro for the most part but came away feeling more positive than he did. The set pieces, digital or otherwise, are simply phenomenal. It is definitely one of the more breathtaking movies I've seen. But, as Pyro said, you already get that sense from the trailers.
The movie was mostly well acted, but I had issues with a few of the characters and some of the scenes. It is an overly long, and fairly slow-paced movie, but even with that I felt like they left out some important bits on the cutting room floor and didn't cut some stuff they should have.
[spoiler]Charlize Theron's character was a complete waste, though it's always nice to look at her in movies. One part that really surprised me coming from Ridley Scott was the whole "Luke, I'm your father" scene with Weyland and Vickers. First of all, it was really poorly executed. Everyone could see it coming a mile away. Worse still was that it basically was completely inconsequential. It didn't have any bearing on anything whether or not Vickers was Weyland's daughter, because Vicker's character was very wooden and undeveloped. And speaking of Weyland, he was a slightly less useless character. The supposedly posthumous hologram thing they did with him at the beginning , but then they reveal that he's actually in cryosleep on the ship. Again, the execution was poor. There wasn't a strong feeling either way about his character and so his physical, live presence just didn't really matter. He didn't affect the plot either way and his makeup was horrible.[/spoiler]
In the end I'm very biased because Alien and Aliens are two of my favorite movies, but despite the movie's issues, I did come away being intrigued by Ridley Scott's new direction for the universe and wanting my questions answered.