When I first watched Aliens, it was only a day or two after watching the original.  I expected more of the same, but I was poorly mistaken.  Aliens and Alien are very different movies, and this is a good thing.  Aliens is chock full of action, death, and strong character moments.  It's super tense and a little scary, but the flashy explosions and gunfire are the main foundation for this movie's entertainment.  After watching it for a second time, the slow horror bits became even duller, but it didn't drag the film down too much.  This is a classic action movie, and a great sequel to it's predecessor.