Just returned from a stay at the downtown Dublin Radisson Golden... or whatever they call it. All was fine. It was clean, great location, helpful staff and a nice breakfast. The airport is about 20 minutes away, about 20 euro taxi ride. We saved about 10 Euro on the taxi ride by walking to the main street (about a 2-3 minute walk) to hail a cab.
Might be worth it for those of you with doubts about the airport hotel.