I initially bought the book to support the creator since I didn't care too much about chess, but after learning more I just got hooked. At first I couldn't even beat the sub 1k elo bots, now I'm 1500 in puzzles and I can beat the 1600 rated bots almost every time, so this book helped a ton and for that I'm super satisfied with my purchase.
For anyone that is interested in chess but doesn't know where to start learning, this book is a must. But don't get me wrong, this isn't just for beginners, the level of knowledge you get here can carry you to 1500 elo easily.