I think what I like most about these books is that, even though things turn out all right in the end, actions have consequences and the main characters suffer. Change in fiction arrives through suffering, and while trials and tribulations are the stuff of many dungeon-crawling fantasy novels, the characters rarely actually truly ENDURE anything beyond some close physical scrapes. Liriel goes through a lot of inner torment to try to find her place in the world, and it's compelling. Or, at least, it was to me.