Pfft no, 2001 is perfect. Every time I’ve watched it I’ve been high af, and I fall asleep for a few min at a time throughout it, and I don’t miss anything at all!

I certainly wouldn’t want to watch it sober, though.

I sometimes miss the excellent straight-scifi film that gets interrupted by the horror move that breaks out.

Aliens is quite possibly the most perfect sequel to any movie ever. Rocky II, Terminator 2, Godfather Part 2, Empire Strikes Back, it's up there with the best of the best.

What makes Alien/Aliens special is that they are entirely different movies. Different styles, different feel, and almost an entirely different cast. All those other excellent sequels were continuations of the story, using characters and settings established in the first film. You start with Godfather Part 2, and you'll be almost entirely lost with who is who and why you should care. You can go into Aliens entirely blind, and you'll still get like 90% of the enjoyment. Watching Alien improves the experience, but is actually unnecessary.

And that's part of why it's so good. You should watch Alien, not just for the backstory on Aliens but because it's an amazing standalone film.

It woulda been cool to get some more sequels, but alas...