I found this movie to be entertaining. It reminded me of Trollhunter, another movie on the same subject, but which was perhaps smaller in scale as it involved a small group of troll hunters rather than the entire government of Norway and its military. When it comes to science fiction or fantasy I tend to give more slack for the writing and I found this to be fairly well written and well acted. There were a few clichés about government leaning on the military as their first and only response to a crisis, but in an odd way it is a relief that it is some country besides the United States being portrayed as doing that.
I thought the special effects of the creature and the scenes of destruction were pretty good, though I do not profess to be all that knowledgeable about the world of special effects. The ending of the movie seemed a little anticlimactic and not quite believable to me as far as the final plan to neutralize the troll went and the final scene of there being more trolls feels a slam to the earlier assertions that this was indeed the last troll in existence. But as I said at the outset, the movie held my intention and was entertaining overall. So what more could I ask for?