Having consulted the Rough Guide, Lonely Planet, and the Eyewitness guides to China on my last trip to the country, I can definitely vouch that Rough Guide is the way to go, with Eyewitness taking second and Lonely Planet a distant third. For my money, the Rough Guides have the edge on Lonely Planet in their critical-but-not-jaded tone, detailed practical information (more detailed than Lonely Planet), superior maps, informative and comprehensive background essays, and general elan (subjective, I know, but there you have it). That said, Lonely Planet does seem to have a slight edge in restaurants, but every place we ate at out of the Rough Guide was delicious. In the end, of course, which guidebook you buy depends on the kind of travel you'll be doing; I would recommend the Eyewitness guides without reserve for armchair and group travelers, or for those map-obsessed travlers who compulsively want to find their way around on their own. That said, the Rough Guide maps are more than sufficient, especially when supplemented with local tourist maps, which will inevitably be more up-to-date.
That really is my only caveat about the book; things in China (especially Shanghai and Beijing, cities most travelers pass through) are changing so rapidly that a new edition can't come soon enough. I marked an additional 20 subway stations on the Shanghai map in January 2007; this book was published in October 2005. In the meantime, I'll just say that the Suzhou Museum is now a must-see.