I went to Big Gay Ice Cream quite some time ago and found the ice cream uninteresting, with the chief selling point being the toppings. It wasn’t worth waiting on line for. More recently, people on Chowhound have said the quality of the ice cream there has deteriorated and the place is no better than mediocre.
If you want great ice cream in that neighborhood, you can either go to the very interesting Odd Fellows on 4th St. between 2nd and Bowery, which is an outpost of their Williamsburg location and has a limited but always interesting selection, or if you like gelato, go to Il Laboratorio di Gelato on the corner of Houston and Ludlow, right across the street from Katz’s. Il Laboratorio has something like 256 flavors, with a few dozen on offer each day.