I was in New York two years ago. I happened to hear of Banjo Jim's because I picked up a newsletter when I went on a small pilgrimage to the Mandolin Brothers shop on Staten Island. It turned out they were having a 'mandolin festival' that selfsame night. We went on the subway, which we found easy enough, and had no difficulty finding the place.
I was made to feel very welcome, everyone in the place was very friendly, (in contrast to what I'd been told about New York) and the music was excellent. I'd certainly encourage anyone living in the area, or passing through, to support the place.