i hired out both this and the lonely planet from the local library before buying and decided on the rough guide as i prefered the writing style, which seemed to make it a lot more readable and less factual than the lonely planet.
however once using it i found that it was wrong on a couple of occasions (with trains and comments on an attraction)and that it didnt list anywhere near enough hostels. having had the lonely planet (2006 version) for south east asia which i travelled just before china, i found it a lot more helpful as a backpacker on a budget. and didnt fill the book with hotels and resteraunts way out of the average travellers budget unlike the rough guide.
now this is NOT to say that the lonely planet is perfect as you soon find that these guide books really are to be used loosely, but on several occasions i found myself with other people trying to suss out a hostel or a route and those with lonely planets always seemed to come up with more useful information or better recommendations.
it was still useful at times and i totally recommend a guide book for china but the popular lonely planet is probably your best choice. however they tend to make their listed hostels pretty packed, so i recommend picking up a hostelling international leaflet that lists all of them in China, this proved to be a lot more accesible and suggested some hostels that didnt have that 'lonely planet route' feel to it! (you should be able to pick them up in any hostelling international accreddited hostel or just use the website)
hope this helps