Switched to them a couple of years ago and had nothing only hassle. We were charged for calls that were meant to be free, didn't receive the bills but recieved reminders constantly even when we eventually got the bills and paid them. The number of cold calls we got went through the roof and they couldn't resolve it for us.
Their customer service while very friendly were useless, they couldn't resolve any of the issues we were having, after about 6 months we went back to Eircom and everything returned to normal. Unless they have changed in the last year or so I would steer clear.