I hate to ruin movies, but I'll save you some money.
Aliens meet humans, humans argue with aliens, lots of crap mixed with CGI happens; aliens kill most humans and humans kill a few aliens. One pregnant human escapes bearing the evil seed on one of the aliens so "Promethuis 2: Return of More Crap" can be made by the studio if they can arrange financing.
I've gotta agree with Bob....but after watching that clip, i'll be booking my ticket in the directors section of our local cinema......that looks awesome.....and with Ridley Scott directing it's gotta be good!!