Shanghai seems to get consistent positive ratings.
By a lot of corporate expats, yuppies, and a good number of expats who never lived in any otehr city within China. A few have, but not all. If you want a "western city in China," then you might want to reassess why you are coming here, or look to Hong Kong, which offers a superior quality of life when compared to Shanghai. Caveat emptor.
I have researched Shanghai (this is where I'd be teaching) and talked to a friend who lived there for two years and a few others. I personally think it would be exciting in the city, as most of my days are trapped here in suburbia.
Dalian, Xi'an, Wuhan, Qingdao, Changchun, Beijing, Chengdu - cool cities too, and far removed from western suburbia.
I am not a huge partier. I like to explore and observe.
Well, after a month in Shanghai, all that there is to do is party and explore. After a year, if you were adventurous, I don't think there will be much left to explore in Shanghai.
I don't mind hot and humid. I hate the cold but can certainly take it.
That's good. Shanghai can get hot and humid and grimey in the summer. In the winter, the humidity can make the cold feel worse than it is.
Give it a shot. If it irks you, you can easily relocate given enough time and planning.