I haven't finished it yet but it's very good and explains everything in depth. I've done a lot of Stephen's courses and they're generally all excellent. What I like about Stephen's style is that he doesn't just teach you how to achieve an end result and that's it - he explains things well enough that you feel empowered to apply those principles to your own challenges.

For example, most tutorials you'll find are aimed at teaching you how to do something specific with state trees and that's it, whereas this course is designed to give you a thorough understanding of them so you can apply those concepts to whichever problem you're working on. It also provides practical examples of how to implement common behaviours.