They have rich storytelling in the book but not the game. The Sylvanas book paints such a better picture of Sylvanas and Zovaal. We get to know her motiviations, that she distrusted Zovaal until the end of Legion, that she felt she wasn't part of the horde but played the part to protect the forsaken. And the same for Zovaal. We get to know he was the arbiter and saw it all, saw how bad the shadowlands work with the kyrian doing their job without thinking, maldraxxus only protecting the shadowlands and ignoring all other threats and how families, friends and lovers get separated in the afterlife dispite doing the right things while they lived. Also his prophecies about Sylvanas that became true. In the book it's a rich and compelling story where we get to know the motiviation of the characters, understand why Sylvanas trusted Zovaal and get that tought that maybe he's the good guy after all.
The problem is that it's all in the book that came out when the expansion was finished. That story should've been in the game. Give us a 3 or 5 Minute video where Sylvanas talked to Anduin and told him what she saw when she threw herself off of icecrown and met Zovaal or just give us a piece of paper we find in torghast where we could've read that. It's such a shame that they have christie golden who is a competent writer but doesn't get involved in actually writing for the game but is instead only hired as an advisor.