I really like DUMBO. It has parks, waterfront views, art galleries, a few small bars and converted mill buildings for live/work space. And right down the street is the little enclave of Vinegar Hill. Definitely one of the most hidden or just unknown parts of riverfront Brooklyn.
check out this article about the Commandant's House. We rolled up to the back gates unknowingly and saw the same 'through the gates' views that that website already shows, so I didn't bother posting my pics. completely wild.
Brooklyn's Mansion on the East River