LOL! It's hard for me to see why he's popular (having lived in NYC until about 5 years ago), because he doesn't strike me as a very convinced Republican. But it clearly indicates that people really don't like whatever it is the Dems are selling.
The quality of life in NYC has dramatically improved over the last 12 years. That is undeniable. Times Square is a glamourus showcase, not the cesspool of depravity it was in the 80's. That is something practically every New Yorker sees at least once a week.
Bloomberg is also helped by the absence of out of control police scandals on his watch. No blacks being sodomized with nightsticks or riddled with gunfire for standing in their doorways or shot for refusing to buy drugs from an undercover cop. That has won him black support.