Should I buy and read 'Heroes of the Valley' da 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 più 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 te please tell me what te think of it?
Advanced thanks to whoever risposte :-).