Should I buy and read 'Heroes of the Valley' by Jonathan Stroud?

I'm running out of things to read and I spotted this book at the bookstore. The reviews I've read on the Internet are mixed and contradict one another so... I need more opinions. Also, a lot of people are saying the ending is horrible and a cliffhanger; is that true? If you've read 'Heroes of the Valley', can you please tell me what you think of it?
Advanced thanks to whoever answers :-).