The subway systems in Shanghai and Beijing are very good by international standards. They are clean, reliable, extensive, and modern (although I was only in Beijing two weeks and Shanghai ten days). At rush hour the subway tends to get packed though (maybe London is the only place I've experienced anything similar). Somehow a packed train in Toronto or even New York doesn't feel as packed as Beijing/Shanghai.

If the Kunming subway is anything like Beijing and Shanghai it will be fantastic.

My only beef with those subways is that you often have to walk 5+ minutes to make a transfer, but the subway map doesn't make it clear where the transfers are on top of each other and when they are far away.

The only other city I've ever been in with transfers that are consistently as far away is New York, but at least there you can tell by looking at the subway map where you will need to walk a few minutes.