Interesting posts - I have lived in Beijing and Shanghai for a total of five years (previously in US) and will be travelling to Argentina for the first time. Shanghai definitely has many of the same aspects from what people complain of - dirty, inflation, rude (imagine 23 million people in 1 city), developing relationships/frienships with Chinese people. The big difference is that the outlook for China is very positive, and even if finding a well payed job without fluent Chinese (a much harder language than Spanish), most feel it is the place to be in the world right now. In addition, there is no north american hatred in China. Most Chinese have high respect for the United States - want to study there, and ideally get a high paying job there so they can support their family members buy a nice house/taken care of. Thus, the motivation of the people may be a big difference as well.
I have studied Chinese every week three times for the past 7 years. I am still only 50% there, but it is a language I will continue studying for the next 20 years. I look forward to seeing the world of Argentina and brushing up my Spanish.