Darkmouth is a quaint, rainy, English village where people don't really want to be, and the descriptions of the town and the people give this book a very brooding atmosphere. There are chapters from A Concise Guide to the Legend Hunter World that give some of the back story without belaboring it.
What makes this a great middle grade fantasy is the description of monsters! A lot of readers are interested in reading about them, but there aren't a lot of books about them other than Lorey's Monster Academy or Gilman's Lovecraft Middle School, or the Scary School or Monsterific Tales series. Those books are a little sillier and for slightly younger readers; Darkmouth is fresh, solidly middle grade and filled with just the right amount of explosions and monster bashing.