The Monk and Wongdoer basically became friends because we rode the NYC subway home every day from school. We did this in the 1980s, when New York was only marginally safer and cleaner than the squalid mess depicted (with somewhat alarming accuracy) in ESPN's The Bronx is Burning.
Yeah, we bad.
And so is subway service. We had delays in bad weather and weak to non-existent AC when it was hot, we had graffiti throughout the subway cars and stations, bums living in the stations, and rampant crime. There's been a vast improvement in the conditions of the subway from when we rode it daily, especially in terms of train cleanliness, crime level and AC. But weather-related delays, re-routings, and lack of information make the system a mess today.
The subway is one of the least user-friendly systems in the world. To non-New Yorkers, the train maps are indecipherable. There are too many lines, various re-routings, no in-station displays about delays or next train arrivals like in the Underground or Paris Metro (although the latter is in bad shape too), and generally too little information for the riders. The New York Times article linked to this post explains the problems and brings up another one -- how straphangers are shut off from the world whilst in the subway.