I've read a couple of books by John Connolly which I've greatly enjoyed, and so was pleasantly surprised when I learned that this movie was based on one of his stories. The result was enjoyable, but perhaps not so much for someone who often enjoys watching thrillers and/or horror movies.
The story's pretty straightforward: a recently divorced man moves to a remote house in a village somewhere, and takes his son and daughter with him (it very adequately matches every single cliché you might associate with this, including mommy issues). His daughter explores the expansive backyard, finds a strange-looking hill and starts acting weird. Turns out the hill's actually a burial mound, inhabited by creatures who are bent on procreating with aforementioned daughter.
What annoyed me the most is that it took everyone in the movie forever to figure out that the hill was a burial mound (even though they referred to it as a mound every chance they got, even before knowing what it was). But okay, let's forgo that for a moment. Every single event in the movie takes a while to register with the father, played well enough by Kevin Costner. Also annoying. Events could have been highlighted with giant neon arrows pointing to them, so to speak, and they still would not register with him.
Other acting performances worth mentioning (unfortunately in a negative manner) are the two children. Whoever plays the daughter has little talent for acting, as does the little kid who plays the son (yet that's understandable, as most little kids tend to overact). The creatures from the hill were reasonably well rendered.
The ending was predictable, one which most people will see coming from a mile away. Still, the overall movie, even with all its annoying little things, was enjoyable. Original enough, interesting enough, entertaining enough. Just don't expect anything great, and you might like this movie.