Hm well I know I'm a little late replying here but I would have to recommend this film too. However if someone might be expecting to see a lot of the trolls and expect a whole lot of screen time with them, you might not be too interested in this movie.
You DO get to see the trolls and they look great, but part of why this movie works so well is the mystery behind the fact that most of the people are in disbelief even though they are seeing the signs of the trolls, until a troll comes out at him.
There are some really thrilling and tense moments, balanced out by some comedy. If I'm not mistaken one of the main characters is a comedian (edit- though I am told he is rather controversial, you should not find him that way in this film) and even though this was set in a sort of 'Mockumentary' style I still think it's rather superb
If you are a fan of these kind of movies or are just interested in scandinavian cinema in general check this out asap!