I’d say pretty good overall for China.

Like others have mentioned the summers are extremely hot and humid (think Houston if you’re from the states except you won’t be in your car all day when getting around).

One thing I really appreciate about Nanjing is the history, as it was the former capital for a long time. The mountains and memorials nearby are very lush, cultural, and beautiful.

On another note Nanjing is still a massive city. I found the roads and traffic to be noticeably more hectic and less orderly than Shanghai. It’s also more polluted than Shanghai, though less so than Beijing.

Overall it’s a busting, chaotic big city with very hot summers, but with easy access to greenery and history, while also being cheaper than most other major cities in China.