We went for the dinner and show. Fixed price menu was good if not outstanding. Everyone was happy with their food and the music was great. I saw a review where someone paid $100 for dinner through a tour company, which is ridiculous. Book it on your own for half the price. If you sit in the regular restaurant/bar area you can hear and see some of the music.
Ideal day would be to hike up Gap of Dunloe leaving around noon, and then about 4 hours later arrive back to dinner and pints of Guinness. The music starts around 7pm if you're trying to time around that.