As far as understanding vs not understanding the plot, I don't think its unusual for a movie like this to leave you wondering a bit what the hell just happened after the first watch, then picking up more and piecing things together with the second viewing, etc. Take pulp fiction - definitely a repeat viewing kinda movie, but not many complaints about it since it all ties together so well. With Prometheus, i expected more to be revealed with the second watch, but what i was expecting just wasn't there. It still felt loosely tied together. I was not even left wondering what happens next all that much. Not because i didn't get it, just because the plot was not really executed that well. Still a fun movie to watch, i enjoyed it, but i can understand the plot complaints. Great idea for the plot, not so great execution.