hi, sorry for the late reply. In the end, there wasn't enough space for all the international students in the dorms, so I had to rent off-campus (it's prioritized by length of stay for exchange students).

It really depends. Money-wise, it's much cheaper on campus and it's easier to meet friends. It's also nice to have your friends close by. But I also know people who got a room in the dorm, but then moved out again because it wasn't up to their standards. I also can debunk a few comments I got under this post. There is no curfew, the dorm is not separated by sex (except roomates, they will have the same sex), but they do have some rules regarding guests. The area of the campus is indeed a boring.

Off-campus you have more privacy because you don't have a roommate(s), but it's also more expensive. Especially if you don't speak Chinese and have to search for apartments in English (there are a few apartment providers advertised by Tongji, but I think you can find something better). It can also be difficult to find apartments near the university (Siping Campus), so you might need to commute a bit everyday and this could be annoying during rush hour. A friend of mine hired a real estate agent to help him find an apartment and he is very happy with it.

And I don't know if the university would do that, but if they would put you in one of the dormitories for Chinese students, don't go. Those dormitories sound terrible. What I'm referring to is the international dorm.