This was like reading a dark reflection of the Dreamworks show. In some ways it was very similar while in others it's very different. It was not nearly as cute and definitely not as funny, there's no magical amulet or cool armor... yet it's very interesting on its own.

The trolls are actually scary, even the "good ones", while the Gumm-Gumms are absolutely horrible and revolting. There was a much greater feeling of dread and of the actual damage the trolls could bring than the show ever managed to invoke.

I could do without the final revelation - sometimes a human monster is just a human monster. Overall it was well worth a reading and I can imagine that if I read this as a kid, I'd have material for a couple of months of nightmares :D