Beautiful mess, full of loopholes and other inconsistencies.

Rating: 8/10 (18 March 2018)

The previous reviewer put it right. I'd add to his list the suspiciosly long-lasting camera batteries. We all know that Panasonic camcorders are the battery suckers, right? :) But those left in the Shimmer appear to be sufficiently charged after being left there for a year, even though the last one supposed to be running till the end of its SD card's free space. Unless, of course, the replicant (for the lack of better word for it) turned off the camcorder but then we have to ask ourselves why he would do so and why, if he was intelligent enough to do just that, he didn't destroy the camcorder (and the record) which had quite a damning evidence about his true identity.
Overall, it is a movie that pretends to be a hard science fiction, yet it contradicts even the basic common sense, just like Alien: the Covenant. But the latter was an expensive Hollywood movie which had terrific art direction, and this one clearly doesn't. Interestingly, Garland's previous movie was almost ideally executed in the art department.
Part of the aforementioned problem is the CGI which is uneven in execution. It looks especially cheap in the shots which feature simulated buildings and interiors, as if it was a money-saving measure to avoid building the expensive sets (which it probably was). In a few instances it's bad to the point you have to mobilize all the suspension of disbelief in you to keep enjoying the movie. The mutant bear was a rare exception. It was probably the most intense scene in the movie and the only one which looked perfect.
The parallel narrative of the protagonist's extramarital affair felt unnecessary. It was put there for a reason, no doubt, but what it was remains a mystery to many. It didn't seem to explain anything, didn't seem to serve any good purpose, didn't seem to move the story forward. Those short flashbacks felt like they came from a b-roll or were a pick-up, and were okayed for the final cut only at the last minute for whatever reason the producers had. Also, they were cut into seemingly random places in the movie, so that the movie's already unbalanced pacing suffered even more.
Its cinematography has that distinctive "video" look, especially in the CGI-heavy scenes, and way too oversaturated in general by modern tastes. Maybe it's cool for a Netflix series, IDK, but not for a movie of considerable production value.
As for the ending, I didn't find anything worth explaining there. It's perfectly in line with recent fashion of making an ambiguous ending which can supposedly please both general types of movie-goers: the "optimists" and the "realists" alike. It became a trend since 2010, with phenomenal popularity of Nolan's Inception but It seems to be an overused cliche in 2018.
So, you can think it's a happy ending, if you wish so, or you can think the Shimmer finally found the right form for the expansion into the humans' world (a heterosexual couple of appropriate mating age) and decided to make a fresh start from there, destroying the impact zone itself, as it wasn't needed anymore for its interbreeding experiments.
Overall, it was a pleasant experience and not a waste of time at all, especially for a hard sci-fi fan like myself, and left something to think about after the credits. Most importantly, I decided to read the original trilogy which, many say, is much more complex than the movie. Kudos to Alex Garland for sticking with the genre which is very hard to be successful in. Villeneuve does it much better, though.