Action: 3/3 + Comedy: 1.5/2 + Good vs Evil: 1/1 + Love/Sex: 1/1 + Special Effects: 1/1 + Plot: 1/1 + Music: 1/1 = 9.5/10 or 95%.
Alien held the deck of cards for archetypical fears embodied in a mysterious, brooding enemy. Add to that the abuse of corporate ethics and the questionable morality of expanding the human race into unchartered territory and mankind faces perhaps it's worse fear: discovery of a more advanced version of itself with no goal aside from killing everything it is not. This is how one makes an action and sci-fi sequel- it adds aces. It is nearly flawless. It is one of the best sequels/episodes in cinema, which remains in a league with Empire Strikes Back.