Why Shanghai?

Hey! I'm a teacher possibly taking a job in Shanghai. Can any expat tell me why they love or hate Shanghai? Thanks!

I find Shanghai to be one of the safest and most dynamic cities in northern hemisphere, probably suitable for the age range 30 - 50, offers a lot of business opportunities and one the most progressive cities in mainland China (You dont get to see the real China in Shanghai, soft landing guaranteed  haha) also suitable for someone with zero mandarin.

Cons:
Expensive: Not suitable for low-income earners.
Pollution: Not suitable for those with existing health conditions. Masks/indoor filters are a must (see above: expensive!!)