This 2002 horror story was entirely adequate, although (and this is difficult to say, because I have always hated people who say this) not actually very frightening. The storyteller/director made an interesting decision to keep the nature of "them" and the fate of their victims from the audience until the last few moments of filming. That decision makes sense, because the explanation doesn't allow for the characters to discover it: they're not some legend that can be googled, which is a nicely realistic, if sort of frustrating touch, because it doesn't allow any intellectual movement - which impedes plot movement.
We WANT to know what things are and what they want. Words like "eat us" are thrown around, but without any kind of substantiation, even at the end. People just disappear, after being very, very frightened. Although understanding the nature of a thing makes it less frightening (which clearly isn't the direction to go, here), even progress towards the main character's final *spoiler* captivity would give the plot some kind of suspense and structure. Instead, Julia (the main character) waffles between belief and disbelief, between stability and insanity, and between strength and fear. This type of film doesn't really use that type of realism very well. They would have been better off offering the audience some kind of cosmic worldview to encorporate Them. Even in the ending, the audience is still largely baffled. Well, I was largely baffled.