I don't like the story or the majority of the characters.
The story's foundation is established on a plot hole.
The tone is far too bleak for my taste.
Three characters I've invested myself in have been chucked out. (Even Aliens brought back the cat! Loops being closed appropriately, no matter how minute, is always satisfying. Baton-passing.)
The mo-motion alien is the worst effect I've ever seen in a major motion picture.
A large bulk of the characters are indiscernible.
There is no world-building. Where's WY headquarters? We're on the third film, so we should be seeing some headquarters by now, right? We graduated from data logs, to a face of the company(Burke), and now is the time we see the curtain pulled back right? We're going to get some good, weighty scenes with the CEO right? Maybe we'll explore more of that derelict spacecraft? Maybe we'll see a futuristic Earth? What's going on with Earth anyway? Does it look like Blade Runner? Are we going to get more than one android this time, perhaps? Is Newt now a grown up warrior? Alien had some great sets and Aliens had some great sets, are we going to feast our eyes on some more great sets(No, we're going to be treated to brown corridors). Are we going to get more adrenaline pumping set pieces, a'la Dallas in the vents or Ripley rescuing Newt? Are we going to get scenes that fill us with amazement, a'la the derelict discovery and the queen reveal? No? None of that sounds good, Fox? Ok then.
Now I want to counterbalance my disdain with elements I like about the picture:
1) The acting is uniformly terrific. Any scene with Clemens is magical. His scene with Andrews is magic, as is the "Are you attracted to me?" scene.
2) The practical alien looks great.
3) Dillon's speech is beautiful.
4) Ripley's scene with the rebooted Bishop is great.
5) Loved the Morse character.
6) The gore splashing across Golic's face, and the alien "smiling", gives me goosebumps.