How is the train service from Dublin to Galway.
You might want to compare train timetables and fares with the very frequent Citylink bus service.
If you're flying into Dublin, you'd have to get to the train station in Dublin. It would probably be faster with a bus directly from the airport.
If you're in Dublin, compare the the bus with the train as someone already suggested.
Great train service! Much prefer the comfort of the train to the bus..food/drink and toilets on the train. If you book online, it can be as cheap (and sometimes cheaper) then the bus.