Driving Was Not Bad
As an American that drives an automatic on the right, I was hesitant to rent a car, but it was not as bad as I thought. The City is like a sleepy hollow compared to New York City and Washington DC (where we had just come from). Driving through was the easiest way to see the city, but we also walked and took public transit. This is a great city, with plenty of culture even if the drivers are very reserved, kind, and....slow.
Insider Tip:Parking is expensive. Prohibitively so, in some cases. If Dublin is your only destination, don't rent a car. We toured the entire country and needed one.