I have been to the Elephant Room many times. Basically, it's a dump that attracts great musicians. The service is horrible, the bathrooms are disgusting. On our last visit, we went specifically to hear an incredible jazz vocalist. We sat just over halfway back in the long, narrow room--near the door. We could not hear her sing. Mostly we just heard saxophone and sounds from behind the bar... phone ringing, ice being scooped into glasses, bar/wait staff chatter. We mentioned the sound problem to a staff member who was apparently totally disinterested. I am done with the Elephant Room.
Pros: great musicians
Cons: crappy service, couldn't hear vocalist