I'm talking about the Williamsburg part of Brooklyn.
from Wikipedia-
Williamsburg is home to a thriving art community and is largely associated with one of its main thoroughfares: Metropolitan and Bedford Avenue. Many ethnic groups have enclaves within Williamsburg, including Germans, Hasidic Jews, Italians, Puerto Ricans, and Dominicans. The neighborhood is also a magnet for young people moving to New York City.
Some residents view Williamsburg as a haven for established immigrant families, while other residents see it as an area of exclusive artists and hipsters. Still other residents see Williamsburg as a lively neighborhood with easy access to Manhattan. The sometimes-clashing definitions have been highlighted by a growing population and rapid development of housing and retail that is changing the look and feel of the neighborhood. Williamsburg is regarded by some music critics as an influential hub for indie rock.
As for Harlem- things have changed drastically.
also from Wiki-
After years of false starts, Harlem began to see rapid gentrification in the late 1990s. This was driven by changing federal and city policies, including fierce crime-fighting and a concerted effort to develop the retail corridor on 125th Street. Starting in 1994, the Upper Manhattan Empowerment Zone funneled money into new developments.[28] Finally, wealthier New Yorkers, having gentrified every other part of Manhattan and much of Brooklyn, had nowhere else to go. The number of housing units in Harlem increased 14% between 1990 and 2000[28] and the rate of increase has been much more rapid in recent years. Property values in Central Harlem increased nearly 300% during the 1990s, while the rest of the City saw only a 12% increase.[28] Even empty shells of buildings in the neighborhood were, as of 2007, routinely selling for nearly $1,000,000 each.[29] Former U.S. President Bill Clinton has rented office space at 55 West 125th Street since completing his second term in the White House in 2001.
So neither Brooklyn nor Harlem are as you think. Things have changed man- you need to get out of your house a little bit more.