I love the ridiculously simple line of textbooks. Micro and pathophyz are both worth every penny, and I've liked some of the others as well (their step 1 book is not half bad).
This book, however, made me angry. I bought it for a quick review during my step 1 studying. I read through almost the entire book in one day, the whole time with a growing sense of unease that I was learning nothing useful and was wasting my time. When I looked at the immunology sections in first aid and did some questions, I was disappointed to see that many things I needed to have covered were lacking, and things I had learned were very low yield. At the end I wasn't really sure what the text had been about, but it didn't seem to be clinical immunology.
Furthermore, it wasn't funny. It seems like the authors of this line should make at least a half-hearted effort to be funny or amusing, or at least simple, or else write for a different line of textbooks.
I returned the book the next day. My advice is that relevant sections of first aid will probably be sufficient.