4.5 stars, a very near 5.

This is one of the funniest and most entertaining stories I have ever read. Leblanc is a master of his craft, and perfectly captures the importance of a petty rivalry of geniuses.

The actual capers of the Blue Diamond, Blonde lady, and Jewish Lamp themselves were entertaining in their own right and Sholmes' investigation made sense as a reader, in that it didn't feel like it could only have been solved via deus ex machina.

The best aspect of this book was the dynamic between Sholmes and Lupin. Lupin especially, despite not being the main character of his own book, really shined. I must critique, however, the portrayal of Sholmes. It was clearly meant to be comedic and somewhat removed from the real Holmes, but the issue is that he was more or less the same as his real-counterpart save for his treatment of Watson/Wilson. At times, it felt like Leblanc had a personal vendetta against Watson as he constantly depicted him as a useless, simping sidekick.

tl;dr: One of the best stories I've read all year, save for one or two critiques.