I prefer my English classes to be taught in both English and Chinese, whose advantage is that it is easy for us to understand what the teacher talks about. The teacher first teaches the class in English, and then she explains those that are hard to understand to us so that we get a better knowing of the passage. That will be good for us.
However, teaching the class in two languages will make the English atmosphere not so strong. Some students who wish to be taught in English will be disappointed.
Except for the disadvantage, I think it is really good to hear two languages in classes. It can make us more familiar with the foreign culture.