wrong quote, but now that you ask, the people that dislike Aliens usually have a grudge against Cameron in specific. they didn't like how the cast was pretty stereotypical(not unlike it was in alien), they disliked the way the movie used war themes(like alien was a glorified slasher), and they claim the movie dumbed down the aliens, despite them showing far more brilliance than than the first alien. most of the elements they complain in Aliens were present in Alien, but it's easier to turn a blind eye at them.
in resume, it's a mix of pretentiousness and extreme idealization of Alien as the perfect movie that had no flaws that warps their perception.
I have to admit as a child I loved "Aliens". It is just a movie I feel like I have outgrown. I don't really do action movies anymore. Not my cup of tea.
I dislike James Cameron's use of mother/child relationship in a lot of his scifi. I find it cheese on toast and leads to some of the corniest dialog in movie history. It's not an "Aliens" example because, honestly, I haven't seen that movie in 15 years. Sarah Connor's speech in Terminator 2 about giving birth is up there in my mind with some of the lowest points in dialog history. No one speaks like that. And I remember more then a few moments like that between Ripley and Newt.
I love the 4 days life span of the alien and think it makes the most sense given their growth rate. Mature quickly and have a very short life span. I like the pure instinct/lack of intelligence alien[it was simply looking for a way to reproduce]. I like the lack of queen and structure. I love the morphing the crew into more eggs to continue the cycle. I am not a fan of the Queen/warrior/worker thing. It's probably the fan of "metal hurlant" in me because flaws and all that is how the original felt. Like a really good '70's comic book. Then again, that is what you get when you add Moebius and Giger to a '70's scifi movie.
Plus there is his lack of respect for the intellectual work of others, but that is neither here nor there because the original Terminator is still a great movie, and better then most of the stuff he "ripped off".
In the end it is mostly different strokes. A lot of the charm i found in the original Alien didn't translate to Aliens. Again, be it a different director, different decade, different goals in what you want to accomplish artistically in a movie. And I will be the first to admit that the charm I found in the original Alien is something a lot of people would hate.