I used this book two years ago during a trip that took me from Hong Kong to GuangZhou, XiAn, TianShui, JiaYuGuan, DunHuang and Urumqi, and even though it was useful as a geographical and cultural guide, ALL the prices were way way off for all the places I visited in XiAn and Western China. I don't know about Eastern China, but the prices to most of the hotels and sights/parks were actually DOUBLE what they were supposed to be, according to the Let's Go guide. Big big disappointment there.
I ended up expecting prices to be double what the book said, and was able to plan the last part of my trip pretty accurately.
Another big mistake was NOT to include the PinYin accents on all the city and sight names. In the Lonely Planet, you just look up a section about a city and you get the PinYin for it AND the accents, which are important if you want to pronounce the name properly. I had to borrow a Lonely Planet on China in order to find the names of the places I was going to and write down the tones so I could say them properly. Miss your pronunciation, and most Chinese people won't understand right away what you're talking about!
Note that the Lonely Planet other travelers had was way wrong about prices as well for the whole of XinJiang and GanSu.
I love Let's Go in general, but they need to work on this one a bit better! I recommend this guide, BUT be careful when you make your budget! Expect some prices to be much higher than anticipated, and if you speak mandarin, double check how to pronounce the names of the places you're going to. Have a great trip!