Aliens Special Edition UHD is definitely simlar to the Abyss in how it was handled. I was more wow'd by the Abyss, but I thought there was a fair bit to like in this one as well.
I've seen quite a few negative comments about it but it's really not bad. There is a fine film grain present through pretty much the entire movie but it's much less noticeable than your typical film scan.
Overall, the movie looks good. Most definitely the clearest of any version previous. Some have commented on occassionally waxy moments in faces but I didn't see anything egregious. There are some shots that are just softer and in those you do lose a little bit of the skin surface detail (they also tend to be in shadow more often too, which doesn't help), so maybe that's what they're referring to.
There are some moments where things look a little surreal and "overprocessed", for lack of a better term. Almost with a 3D feel to them. In general, I think the HDR transfer has a lot more contrast than I recall seeing in previous versions. Combine that with what might be akin to some edge enhancement (usually pretty mild) in the AI resampling and I think that's responsible for the quasi 3D depth sense in one or two scenes (in the first 30 min of the movie I noted two). The movie felt brighter overall, mainly due to the contrast. Blacks were good and highlights were bright (occassionally a bit glaring in a few scenes) and I think it causes the dark scenes (particularly those outside the complex) to be not as gloomy as I recall in previous versions. I don't think it's bad, but it was something I noted that felt different. I want to call it HDR doing what it should in terms of increased depth of range in shading but it's also possible they just opted to shift the balance on stuff too.
Audio was... I was engrossed in the movie so I can't say too much about it. It was good. Thin in that older 80s and earlier movie way, but clear and a full mix.
I can see how opinions are going to be divided on the 4k version, but if you wanted a cleaned up and more pristine looking Aliens with a much wider color/contrast range and easier to make out picture, you're in luck.
