To be fair to the China scenario, Yelp is barely used even in other English speaking countries. And my guess is that the most relevant reviews would be in the native language instead of English. Anyways, I was expecting more usage in Canada and London but reviews are sparse and anecdotally few people actively use it as much I do in the U.S. I suppose one barrier is the need to build a sales team to get businesses onboard to customize their data and promoting the use of Yelp for reviewing their business.