As I was coming to China, I felt like I needed to learn some basics in Chinese. At least in order to be able to order a beer and say that I did not know how to speak Chinese. I didn't have that much previous knowledge of the language (I just learned how to say "我是法国人" (I am French) which was promptly followed by a reply in Chinese so...).
I had classes with X-Mandarin for around 100 hours. The teaching method can vary in function of the professor that you end up with but I personally only had great teachers that spoke English well enough. For example, I am more keen on doing role playing scenarios in order to use the vocabulary I currently know. There is also a manual that can use as a support during classes, which follow the different levels in Chinese (HSK 1, HSK2...). The classes are tailored to your level so you won't be thrown into the wild and they can help you if you have any question. In the end I feel that I have made a lot of progress in Chinese.
The sole issue I had is that I changed of professors 3 times, but I always managed to get along the new teacher.
On the side, some events are organized by the school, such as a trip to a local park, which is pretty neat.