I read them years ago, and found the series a pretty uninspired generic fantasy quest. As I recall, in just about every book, the heroes eventually find a way to defeat Zagor, but then it turns out that he's found a way to come back even stronger for the next book.
It's amazing how much better the Legend of Zagor gamebook was than these novels. The gamebook made the first two in the series seem so much more impressive than they actually were having waded through them.
Unfortunately yes. The picture book, the Casket of Souls that was in the library of my junior school was also much more intellectually stimulating than any of the Chronicles. At least the reader felt they were getting somewhere by reading it. They get to be the one to trap the demon.
Heh, I remember when I'd special-ordered A Casket of Souls from a local independent bookstore. When they called me to say it was in, I promptly went down, and announced to the elderly lady who was clerking that day, "I'm here to pick up A Casket of Souls."
For some reason she gave me a somewhat alarmed look... and then a relieved one when she realized I was talking about a book.
I remember reading them. Zagor isn't even in the first one - it is all about the Casket of Souls etc. The characters don't get much development and the wizards and magical items seem grossly overpowered compared to anything else in canon - being able to summon earth elementals, having magic arrows that split into twelve arrows etc. In hindsight, they read like reports of dungeon crawls.
When writing Dragonlance, Weiss and Hickman had the good sense to skip the bits of the story that seemed too dungeon crawlish and focus on the character interactions and drama.