We read the first book as a bedtime story, both DS6 and DS4 *LOVED* it! It is a bit fantastical, but it's a kids book and my boys are both still young enough to accept crazy twists at face value. I read the 2nd book right after I read the first one and thought it was a nice book, not quite as well written as the first and a bit more intense, but nothing that would preclude recommending it. I think the books are definitely for younger GTs though, the twists are just too hard to believe for most of the older kids.
There's also a website with some games on it, though DS6 didn't really get into it.
http://www.hachettebookgroupusa.com/features/mysteriousbenedict/content/index.asp
