This was a good book but not a jump out of your seat, run the nearest bookstore and hold a mini protest until they give a copy kind of book. It's good if you're bored though. The writing style is simplistic and the book shouldn't take too long to read. I'm expecting the series to go downhill from here though.
I was surprised to learn that Cassie is English, I was expecting the story to be all-American. It was also nice that there was no love interest (cue gasps of horror) in it. Well there were two but she didn't get with either of them. And! One thing that is awesome! The main bad boy mystery character... is Indian! Too many pretty white boys in books, time for some pretty... not so white guys.
The mystery in the book is very basic and slightly clichéd. It all went a bit Scooby Doo at the end, ironically. The characters are very stereotypical, acting in a way that mirrors the stereotype of their country. Cassie and Isabelle are the best characters and Isabelle is pretty funny at times.
The idea that the school moves to a new city every year is an appealing one though. The amount of bookshops across the world you could visit!