I just watched it two weeks ago. Still holds up for me.
One thing, the pacing is very different. Nice slow burn. The other, I got to know the characters. Another reason, they actually SPOKE to one another, made decisions TOGETHER.
That's not the movie I saw. They never once made a decision together -- they just barked orders at each other, and argued about them -- nor did they stick with a decision once it was made, which was what pretty much always got them killed.
Not to mention sitting around leisurely on several occasions, navel-gazing, while the alien was freely roaming the ship, especially in the first few scenes following its birth.
Or the inexplicable things like a room with gallons of water falling from the ceiling, that a) is happening on a space ship, and b) no one seems terribly concerned about.
I'm really not trying to slag Alien here, just holding it to the same standard.