Should I buy and read 'Heroes of the Valley' 의해 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 더 많이 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 당신 please tell me what 당신 think of it?
Advanced thanks to whoever 답변 :-).