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.
Bloomberg has benefited from Rudy G's hard work. Now, there's a mensch. But most people in my neighborhood saw Giuliani as an extreme right-winger. You'd never convince them that he was anything less than a hard-rock conservative, and when I suggest this, they think I'm out of my mind. Bloomberg is a decent manager, but arrogant and, I think, quietly enriching his friends with under the table real estate deals. I don't like him but will probably vote for him. Ferrer's brilliant ideas include putting a tax on stock transfers -- a great way to drive the financial center to New Jersey -- and giving every school kid a lap top computer. (Half would be sold on the streets within a week.) He is pathetic but, believe it or not, far from the worst of the Democratic field.