If you like movies about ghosts, death, or if you're a teenager, or especially if you loved the Leftovers, you might like this.
The premise was good. Frankly, it was the premise that kept me watching the whole time. I was curious what they were going to do with it.
However, the plot had so many elements to it which were stupid or unbelievable, that this movie ultimately felt like a waste of time. In retrospect, I don't think it was worth watching past the first 15 minutes. Additionally, the characters, while well acted, were dry and not very interesting. I don't think any of them really had much of a personality.
The horror element to this was decent. They did a good job with convincing you that the remnants were really there, and they did give me a bit of a creeped out feeling. There were a fair number of jump scares also, which while slightly annoying, were pretty effective.
I will try to get into some of the plot issues I had.
1) The classroom scene of the "laws of remnants." First off, none of the "characteristics" of remnants were laws. A "law" in science is a generalized rule to explain a body of observations in the form of a verbal or mathematical statement. There was nothing mathematical about "Remants can't affect the world".
2) The explanation of where the remnants came from and their characteristics were delivered to us in an extremely heavy-handed form. From the beginning they explained exactly how the remnants came to be, as well as all of their characteristics. Normally in movies they leave a bit of mystery to things, which enriches the plot and piques your interest. They didn't really do that here.
3) In the beginning, the heroine's friend warns her of this guy who is supposedly "obsessed" with remnants. They never showed any weird behavior by him, except that he was watching them in a tunnel. I would think that every teenager would be pretty impressed and curious about remnants, so I didn't see why he was singled out for this.
4) Why is it that every remnant who appeared matched their physical surroundings perfectly? The dying girl climbing the ladder: Is it really plausible that in this apocalyptic dump, they would leave that ladder in the same exact position? Is it plausible that her father's chair was always positioned perfectly so he could sit in it? Normally we push in chairs or move them around a bit.
5) Why does the scientist at ground zero run from them and then pull a gun on them? And then suddenly is fine telling them the entire story? And why was he watching this remnant get strangled? And why did he choose to live at the dump? He said it felt like the best place for him. Sorry but it all just seemed weird.
6) The whole possession of people with the same birthday thing... Why would someone's birthday being the same allow a spirit to possess them? And why is this scientist so convinced people can be possessed in the first place? Even if I accept the premise of remnants, it felt childish.
7) There was one point where she asks him "Why do you have bolt cutters?" as if it were a strange thing. They had already planned to drive to an apocalyptic city with unknown environmental situations. Of COURSE he should bring tools to deal with unanticipated situations. A better question would be "Why didn't you bring a gun?"
8) It seems bizarre that the informant of the girl who died said to them "Do you want to see her die?" She can easily explain how she died. Why did they need to drive out there to see that? Even if it did make sense, it just was a weird way to phrase that about someone they cared about.
There are a lot of other little things like this which overall degraded the believable-ness of the film, and thus I had a hard time caring about the characters. Also - that scene where the guy forced her to kiss him... That felt creepy and wrong on his part. I definitely did not ship them at that point.
Overall though, it was mildly entertaining. And the premise of having ghosts that everyone could see felt like an original concept in a movie. Unfortunately they didn't do the best job with the plot.
I feel that teenagers could probably enjoy this movie more than most adults due to the high school situations.