I've lived in NYC for college for the last two years. Personally, I love it, though many of your criticisms are valid. I'll just address what I can.

the water is polluted

I drink tap water from the sink all the time and have never had any problems.

To walk anywhere, you must wade through a sea of drab, disheveled humanity. The public transit is packed.

If you take the subways during rush hour, then yes, it's crowded. But at literally any other time of day, I've never had a problem finding a place to sit on subways and buses. In Manhattan. Also, as long as you avoid Times Square or traveling through any major protests, there's room to walk.

Also, many of the people are interesting. I've never thought "drab" as a description for New Yorkers. There's always so many things to see- public areas are alive with music, performers, and even just really eccentric looking people.

Then there's the climate. The winters are frigid and soul-crushing, complete with biting wind and extended periods of low sunlight or darkness. The summers are sweltering, and the heat only exacerbates the ever-present smell of rotting garbage.

The last two winters may be a poor measure to judge New York by- they were both unusually cold, with winter 2013-2014 being among the coldest in the last 50 years, and winter 2014-2015 having the coldest February in recent years. Even then, it doesn't quite compare to the kinds of winters seen in the nation's heartland. I admit that I'm away for much of the summer, but in terms of heat/humidity, I doubt Boston is much better, and I can assure you that the South and the Midwest are worse.

Other than that, you're pretty much right.