I own the first four books and they're just the right length to get you in over your head on a topic with enough knowledge provided so that you can pull your head above water and not sink into the abyss of web nerdery that can so often overwhelm you.
This is definitely not me dropping hints for this collection. I already have the first four on my bookshelf. I guess this could be a subtle hint for book 5 but I still have to finish the first 4 books. ↩