This remains, to this day, the most enjoyable movie I have ever watched. Not necessarily the "Best" movie (sorry to be cliche, but that is Casablanca) but unquestionable the most enjoyable. There hasn't ever been another movie that has gotten close.
I seriously cannot even think a nit to pick. Well, maybe the gratuitous underwear scene from Sigourney at the end but ... who's to pick.
This movie was far far better than the original (Alien) and probably is the best sequel movie ever.
10/10