Trolltider is an advent calendar series with a pretty mixed quality. While I understand that the budget was quite slim (probably), the world of the trolls is quite boring, cheap and simplified.
The backgrounds are blurred in many cases which seem to have been a way to get away with making things less detailed. Then there's the troll village, that is quite decently made, but it lacks in size and you can tell that they had to reuse a very small area a lot of times in the series.
Also, whenever we are in the trolls world, it feels like a sitcom, and when it's in the human world, it feels more movielike. I don't know if it was a concious effort to make it this way, but the troll world comes of as cheap.
The stone trolls look like something from a show 20 years ago, as they lack any realism and horror that they are supposed to portray. And while it is a family show, they should have dared to make them much more menacing. I can't imagine a 5 year old being scared of them, which might have been the idea, but I also can't imagine a 5 year old even understanding that they are the enemy. They are simply too dull, inanimate, and doesnt seem to be the threat they are portrayed as whatsoever.
Overall, it's a pretty mixed bag. The story is great and most of the actors are great, but it's not quite there. I really wish it had more runtime as 10 minutes is too short for many to get emotionally invested and I also wish they threw some more resources on it. It feels like they went almost all in with it, but I think everyone wants SVT to go ALL IN, as they did last year, with a convincing world that felt much bigger, lifelike, and where there was a real sense of danger.