University Teaching
Probably the most rewarding and stimulating teaching jobs available in China are those teaching in state-run universities. Only the most able of Chinese students are able to attend a public university, and you will hopefully (though I'm not making any promises) meet classes of bright, eager students who've worked hard to get to where they are. This is almost certainly true if you are teaching at a prestigious insitiution.
Public universities tend to offer significantly lower salaries than private institutions, and make up for it with less working hours - 12-16 is the norm, as opposed to 20-25 elsewhere. This extra time gives you a bit more flexibility to study Chinese, take some freelance work, or catch up on your DVD watching. If you're lucky, you'll be able to wangle yourself a three, or even four day weekend.
It's worth asking if you will be teaching English majors, or students of other subjects. All students in China have to study English, and you may find yourself faced with a class of computing science students who, friendly as they may be, would much rather be grappling with programming languages than foreign ones.
The English majors (theoretically, at least) should be more interested in their subject and able to tackle much more challenging material - literature and discussion classes, for example. However, I sometimes suspect that a lot of English majors were not so much interested in English as undecided what to take, and thought that English seemed like as good an idea as any.
Private universities / colleges
Private colleges and to a lesser extent universities are becoming ever more common in China. Broadly speaking, they do not have a very good reputation, and are the option for those who do not get into public universities.
There's a tendency to write these students off as 'failures' as a result of this. While it's true they may be failures as far as the university entrance exam goes, it's worth bearing in mind that only the highest-scoring few get into the public universities, and it hardly seems fair to discard the remaining students on this basis. While some of the students I have seen at the back of the class in private colleges did appear to have been dumped there by affluent parents to avoid them taking up useful oxygen at home, there were many more at the front trying very hard to succeed.
However, it's not just the students who are responsible for the poor reputation of these institutions - inefficent and incompetent management much more familiar with balance-sheets than blackboards cause the most serious problems. If you spot a job you like the look of, then go for it - but bear in mind you may spend more time working against your employers than working with them.