You can be in the center of Dublin in just over 30 minutes from the airport by taking the AirLink Bus. However, a taxi can often be quicker, depending on traffic (taking anywhere between 20 and 50 minutes), and cost you between 25 and 40 euros.
Better than a taxi is booking a private transfer, so you know exactly how much you'll be spending beforehand:
Transfers from the Airport
If you don't wish to rely on public transportation and prefer the convenience of a transfer, here are your options:
Getting Around Dublin
You can then walk from one end of the city to the other, but if you feel the need to use public transportation, choose the Luas, the city's sleek light-rail tram system.
To go elsewhere in Ireland by car, check the cheapest rental rates: