I'm not at all disapointed! Why would I want to see something I already know. I want to see monstrous creatures that I've never seen before, killing people in new innovative, creative and un-imaginable ways!
And i'm very curious about the spacejockey's race, and what happened to them etc. etc. Don't really care about the whole 'where do we come from, god vs. science' pitch. Hollywood doesn't get science.