I am leaving this year and environment is the main factor – air, water, crowds, noise. Recently we couldn’t take my 1 yr old daughter outside for 5 days straight because the pollution was so horrific. But you should also be aware of the water quality issues and general safety issues for children. And get ready for incessant and irritating construction noise, everywhere, all the time. You may hear locals telling you about how Shanghai has some great parks. This is of course based on never having been to a park outside of China. I think Century Park is the only one that is even half decent. The others are generally small, crowded and full of nongs walking around blowing smoke in your face.
If environment is important to you, you shouldn’t move to SH. If there’s no (significant) financial advantage, then you certainly shouldn’t be looking to move to SH. After 2.5 years here, every day I hate this place a little more. I don’t think there’s anything worth being here for except money.