I heard the buzz like everyone that James Cameron had destroyed another one of this films through heavy grain removal and smoothing of the picture (T2). Now usually I love grain in my movies and enjoy the crisp look of film. However I feel for the most part, the crisp or detail here is still intact without the grain. With that said, yes there are a couple scenes which are brief where Ripley or someone else will have some glossy skin and just look unnatural. But this only happened a couple times briefly for me.
I was amazed at the incredible detail and how clear it was! It was like watching a NEW version of the movie I hadn't seen before. Now seeing NEW details in scenes I had never noticed previously. Looking like the film was shot yesterday.
Now I know some out there don't want Aliens to look like it was shot yesterday and I sympathize with you. Most of the time I would agree. And I though the previous Blu ray release was a decent release. That one was full of grain, It also had a blueish hue to it that I think served the film well atmospherically.
The only issue (Other than those two brief moments of glossy faces), is the Film now has a teal blue hue to it which I wasn't a big fan of. Now you get use to it of course but when you go back to the previous blu ray, you can see the difference is night and day with the color grading. And I much more prefer the blue hue in the previous blu ray vs the new teal blue hue in the 4K. The trade off is that the picture quality is incredibly clear with immense detail and the clearest version of Aliens that exists. After seeing the 4K, however it may be difficult to go back to the blu ray since its packed full of grain. But if you prefer that than definitely hold on to the blu ray or look for that version to own.
I am an Aliens fan and I was just curious about what all the controversy was about. I myself are a stickler for High quality transfers and with most older films, grain is important.
My advice is if you are really on the fence about it, or don't want to spend the money, borrow it off a friend or family member and see for yourself if you like it. Or I believe the 4K version is on Disney + so you can see it there.
I thin regardless of your point of view, it's worth checking out.