Prometheus is a high concept Sci-Fi film set in the same universe of Alien, Aliens, Aliens 3 and Alien Resurrection. The Alien Vs Predator universe appears to be a separate time line as if that stuff had happened the events of this movie would be significantly different, so don't try to fit that stuff into cannon and I think the Predator(s) films probably feels the same way.
I liked the movie and felt that the special effects and pacing were good. It was filmed in 3D same as Avatar, so if you're looking for that immersion feeling go ahead and watch it in 3D. Personally I don't find the 3D effects really do very much for me, and since I don't remember things in 3D it seems like extra money to wear some goofy glasses for a few hours.
Spoilery stuff stop reading here if you don't want spoilers. Ridley Scott has really added an interesting religious subtext to the movie which is explored in depth in this review over here:
That's all good and lends itself to some stuff to look for the second or third time you watch the movie. For me though, I'm going to a movie in the Alien(s) universe to see some Xenomorphs. I've been fascinated by HR Geiger's design work for years and I was looking forward to some spectacular new set pieces and imagery. Aside from an expanded Space Jockey and a mural seen briefly we don't get a lot of this though. The Engineer design evokes the classic image of a Titan or a God and that's cool and all, but it can be a little boring when you're going in hoping for lots of bitey teeth stuff. And while there is plenty of blood guts and creature action to enjoy in the movie a lot of the actual monster stuff gets a bit confusing. For example if you blink when they first walk into the room with the jars, you'll miss the worms on the ground that it is assumed turn into the snake like face-hugger things later on. I would also postulate that it is because of a regenerative property of these worms that the snake is able to regrow it's head to continue attacking the glasses science nerd. But as we are not shown what happens to mohawk geologist nerd after the acid blood melts his faceplate it's kind of a surprise when he shows up all super bendy murder death kill later on. It's left to the individual audience member to figure how the bio-weapon seed in the jar is mutating and affecting each individual it comes into contact with.
Anyway, in summation this is a big movie that is getting some very mixed reactions from the audiences. It deserves to be seen and I do recommend it, it is a long awaited addition to the Alien mythos.