I've also tried to read the books and got some way through them, but without an awful lot of enthusiasm ... it all seems a bit jumbled and hashed together any old how, without much of a believable story arc for the main characters to develop through. I remember being really annoyed at how quickly the pink-cheeked kids from the village in the mountains suddenly became unstoppable warriors and the huge killing-machine trollocks became standard fodder for them. I felt there was too much going on, too many wacky ideas (some original, some lifted untouched from other stories and just plopped in) just lumped into the wider story and it didn't seem to fit together very well. I'm afraid the dialogue and general writing was quite average for me as well.
The TV series ... I've only watched the first episode and thought it was fine, a decent bit of chewing gum for the eyes and the 7/10 it got on Prime was probably about right. As other people have said, the younger cast appear to be dragged along by some of the better actors and it's a shame since they're the core of the plot. It has indeed also suffered from a lack of explanation as to the history or background of the world in which it's set, which is hardly new in book adaptations.