I love NYC. I also like getting around on subway – usually, it’s very efficient. I don’t like the heat nor do I like the crowds in rush hour, but generally, it’s pretty good. Best thing is that it zips through traffic and is rather predictable.
However, when it’s hot in NYC, as it was this week (and is most of the summer), the subway is not such a “cool place” to be. The trains themselves are air-conditioned, but the platforms are not. Other subway systems in the world dealt with this issue (usually in newer systems) – not NYC.