This was one of my primary resources for a 10 day trip to Hong Kong. I am lucky to have 'an ear' for the tones of Chinese languages, but this book helped to provide me with enough vocabulary to communicate in simple Cantonese and be understood. You should understand that the Cantonese speaking regions of China are a madhouse mix of languages and accents, and if an elder Hokkienese speaker doesn't understand your mangled "Guangdonghua" it's not the book's fault, it's just part of being in China. :-)
Overall a very helpful resource at a good price, fairly durable and fit easily into a hip pocket or belt-pack.