This book got better as it went along. At first I thought the author was a little too enamored of how cute he was being. As the story picked up, though, the showy cuteness dropped away some.
This was a good mystery for my kids. Some shadowy bad guys who are thought to have killed someone, but there's some evidence the guy's not really dead, and a boy-and-girl detective team that is still slightly too young to be interested in anything but being friends. Although the culminating conflict did include the threat of killing a kid by sticking instruments up his nose and rooting around in his brain, which might have been slightly excessive.
Anyway, there are more books in this series and my kids want me to read them out loud, also. They're hard to get a hold of at the library, though, and our local library started charging for placing holds (unless you do it in person, which goes against every economics lesson I've ever had, except for the one about "entrenched special interest groups").
Rating: six out of seven giant inflatable monkeys.