I lived in Dublin for one year, and this was definitely one of my favourite pubs.
They often have live gigs, and then on Fridays and Saturdays it turns into an alternative/indie/rock dance bar as well as a pub just to hang out with your mates. On that note, be sure to be there before 10pm on weekends [don't worry, you definitely won't be the first one there!] to avoid paying to get in.
They also filmed a scene from the move "P.S. I Love You" here.
phone number: (01)4780766