I live in Lucan and have ntl broadband. It was installed within a couple of days of ringing up and we had no problems from the start - the speed was ok.
Then, along with the digital tv, they both stopped working. The tv came back after a couple of days but the broadband was broken for 4 weeks! We were ringing every second day but they could do nothing for us other than book a technician to come out and see us - in 2 weeks! Was really unhappy with their customer service.
The technician came out and stayed 2 minutes, basically said "I've been in about 5 houses in the area today and this is happening in everyone of them. The signal strength isn't great in Lucan but give me a couple of hours and I'll sort it out"! Fair play to him though, I don't know what he did, but everything has worked fine since (bout a month a half) and the broadband is faster.
I wouldn't recommend NTL though. Everything is ok now but I just know another problem is around the corner. I'm with them over 4 months now and I have received no bill! They also told me they would refund me for the broken broadband but I'm not going to hold me breath! Save yourself the hassle mate.