You can carve the Chinese restaurants in Shanghai up a million ways: by the region of their cuisine, by how traditional or modern they are, by how obvious it will be to your guests that you are spending a lot of money on them (and so they better agree to that business deal / marriage / job offer).
Another classification is by how specialized they are. There are restaurants that do (or are only good at) just one type of regional noodle, or have a very specific method for preparing their duck, or do crayfish and little else. It’s not the fanatical Japanese approach to achieve perfection but it does result in a restaurant landscape of one-dish wonders.
Not much ties these places together except that they are specialists in what they do and that they are about a ten-minute walk from People’s Square, the center of Shanghai.