I am an adult who enjoys a well-written story intended for kids. The Extraordinary Education of Nicholas Benedict is just such a book. I thoroughly enjoyed listening to the audio version.
I have read the first Mysterious Benedict Society book, and while I liked it okay I was not persuaded to read the next one. I didn't realize this was a prequel until I had started it. In my opinion, it is better than The Mysterious Benedict Society. You definitely do not need to read the later books to enjoy this one.
Nicholas Benedict is a precocious nine-year-old orphan with genius intelligence. He is just arriving at a new orphanage, which has recently acquired a new director. There are many problems at the orphanage, along with a missing inheritance from the woman who used to live in the orphanage manor. The new director is furtively searching for the missing treasure, so Nicholas begins his own search. Like all book schools and orphanages, this one contains a gang of bullies. Nicholas get the better of them and is ostracized by all his fellow orphans, due to intimidation by the bullies. Eventually Nicholas makes some friends, solves the secret of the treasure, and fixes most of the orphanage's problems.
The Extraordinary Education of Nicholas Benedict reminded me of the Lemony Snicket series, but it's better. (I enjoyed the first few Snicket books, but grew increasingly less impressed and loathed the final book in the series.) Extraordinary Education also has a Roald Dahl feel to it. Implausible but nonmagical things happen. Even though I easily predicted some of the plot developments, it was still fun getting there.
My opinion may be affected by the excellent audio edtion. It kept me entertained through two long car trips.