The real deal for jazz! We chose this club because we feared the others in more central locations would be too 'touristy'. We came for just drinks and jazz, and we saw Emanuele Urso's 7-piece 'Benny Goodman'-style swing band. They were INCREDIBLE! We paid €10 each entry charge for the music (well actually €15 each in total because we chose to stay when they started the show a second time at midnight).
It's true that the service is quite slow and forgetful, so when they were too slow with my beer I just went to the bar to remind them! There was no service charge added on the drinks.
We didn't try any of the food, so I don't know if it's any good.