Value for the money, the O'Callaghan is an excellent choice of hotel in Dublin.
Loads of good points to extol (I'll leave that to the other half), but I'll just mention some unexpected discoveries:
Sometimes "quaint" isn't so much appreciated.
Not yet sure if this is an Ireland-only thing, but when asked, this hotel "doesn't do washcloths". =-O
They were happy to provide extra towels though.