Not my favorite dive bar, but I definitely see what people really dig it. Copacabana is great for sitting down at a table and sinking a few pitchers of beer with your friends.
Also, their kitchen serves up some surprisingly good Indian food for a dive bar. The pakoras are some of the best I've ever had.
I'd recommend Copacabana for a pre-night-out snack and pitcher any time -- but I'd stress the importance of moving on if you're looking for some real action.