Its a decent resource but you're paying $15 for a 44 page booklet. I guess we're paying for what the book will eventually become. It isn't much different than any other beginners coding book where the examples mostly involve some kind of print function.
I like his videos on YouTube, which are one of the few resources available for playdate programming, so I try to look at it as donating for those videos and getting a booklet thrown in.
If you're a beginner, like me, then I recommend also checking out Pico-8, which I only recently heard about, that's also coded in lua. Search here for mboffin's top-down adventure game tutorial, and his tutorial carts. Then use ai to explain whats happening. Take small ideas from those carts, and the ai explanations, ask "how do I..." and "What if?" questions, then make your own tutorial carts and save them in a folder. This is more useful than writing print() code.