It's not bad, certainly better than author Rick Riordan's other series, Percy Jackson and the Olympians, which I found ghastly and unreadable. To be fair, I started it after working through all of Anthony Horowitz's Alex Rider books, which I loved. Riordan oversees the story arc, but he is only one of the writers that Scholastic is using to churn out the 10 book series in 2 years.
Time magazine described the series thusly: "If you forcibly interbred Lemony Snicket and National Treasure and chose the most viable of their mutant offspring, you might come up with something like The 39 Clues." Orphans Dan and Amy Cahill discover at their grandmother's funeral that their family is old and powerful, including seemingly all of the major figures of history. The will sends them off on a dangerous worldwide quest to track down the 39 Clues and find the Cahill Treasure, the secret of the family's power.
I found it interesting enough to create an account on The 39 Clues website. I felt a bit creepy scrolling all the way down to 1964 to select my birth year, but the site doesn't seem to be judging me. It asked me a series of questions to determine which
I'm guessing it was a close call between this scientific branch and the Janus branch of artists and performers.
The second book in the series comes out today.