If I had to choose once place to eat in Shanghai aside from my Uncle's house, it would be Mao Long. Not only is this restaurant a authentic Shanghainese cuisine, but its local atmosphere also gives the restaurant a down-to-earth vibe.
Be prepared to wait at least an hour alongside local Shanghainese to get a table at this tiny hole in the wall family-run restaurant. Be sure to order the delicious river shrimps (small but savory), house specialty pan-fried pomfret, delicious Shanghinese-style garlic clams and soy-marinated duck. Don't be put off by the simple decor, the food is well worth the trip.
I have to warn would-be visitors that if you go a bit earlier or later to avoid the lunch or dinner rush, the service will be better. Because the restaurant is so small, expect the hostess to rush you to eat (as there is often an impatient crowd outside). Not that this is a good formula for business, but the restaurant is tiny and I do sympathize with the owners as the restaurant has become more popular over the years. Expect to spend about US$25-US$50 here for two people depending on what you order.