The first three books are bit like the first Eragon one to me: kinda naive, not trying too hard, have the certain atmosphere that’s just fun to read, you can forget the real world shit for a moment and just enjoy a nice little story time. Not high literature, but pleasant enough - just like you said, good kids stories. Then comes the latter parts, and the whole thing just gets more and more complicated, and the magic dies off and you forget what happens because it’s not interesting. Bah. At least I haven’t heard of Paolini becoming a raging transphobe…