Book #1 of this series ("The Case of the Case of Mistaken Identity") is such a fun read! I've used it as a read-aloud in my 4th class two years in a row, and it's a hit! I always conduct a fake Amazon review with my students when we're done with a read-aloud to get their feedback. All but 2 of my students gave it 5 stars. The 2 girls who didn't rate it 5 stars said it was because there weren't any girls in the story - which is true. But the rest of my students (including 11 other girls) gave it a hands-down 5 stars - and I agree!! It's a fast-paced story with loads of adventure and plenty of comic relief. Several parts were laugh-out-loud hysterical!I went ahead and bought the whole series for my classroom library because I knew my students would want to read the other 3 books once we were done. Sure enough, I had to hold a drawing to see who would check them out first. I practically had a riot on my hands! Kids just LOVE these books! As an educator, I HIGHLY recommend them!!These books are perfect for a young boy; great mysteries, fun characters and suspense. Great for a gift.We have had some excellent times reading and re-reading these books. My son - who is 7 - just about gets them, but needs a few things explained. Best though is that they will become more in depth as he ages a little. Worth itWe absolutely love Mac Barnett Books and this series is no exception. However, book #3 , It happened on a train, is defective! The printing company messed up the pages and we have no pages 54-86! We have later pages twice.... My son is completely beside himself as we were will into this great read. We are 2 days past the Amazon return window and can't find a way to have this remedied. Very disappointing!Our 10-year old has been reading these books happily! They are like Encyclopedia Brown in style, but modernized. Our 7-year old (who is an excellent reader) said they were too scary for him.My 13 year old daughter loved these books.My 8yo son thoroughly enjoyed reading this set. He said it was exciting and very funny. (And "no bad words.")My 11 and 13-year-old grandsons enjoyed the first book very much--so did I!Arrived quickly and was great price. My kids love these mysteries and were delighted.