I've been to Shanghi but for like two days only so I didn't get to see much and plus when I was there they were doing major construction but the places I did go to see for sightseeing was Yuyuan Garden and the view at the waterfront at night.
I haven't been there before, but I would LOVE to go there one day. For food, I heard "Jia Jia" has really awesome 小籠包 (Siu Lung Bao) and 水餃 (Soup Dumplings). And if you don't mind street food, you can visit 吳江路 (Wujiang Lu) close to 南京路 (Nanjing Lu). I'm sure there are more great places, but just these two I have heard about (good reviews) and would be THRILLED to visit. XD
Went there with a tour, went to other less developed cities prior to going to Shanghai on our last day. We were only at Putong, which is like where every nice looking thing is. Then we went back to the West side I hink and it was all factories and shit... we stayed at a 5 star hotel in that area too lolz. But the cityscape of Shanghai was beautiful when I was there like 2007. Should be much better this year because they are hosting the world trade festival.