We have lots of discussions about car rental on this forum, and I just wanted to share my recent experience. I rented from Budget at Shannon airport. I was the only customer there at the time, but I still got the impression that I was an inconvenience that they wanted to hurry out as quickly as possible. I got this same attitude from the desk staff in the airport as well as at the pick up lot.
   The car they gave me hesitiated to start at first. I went back inside and the woman told me it was because it hasn't been started in a couple weeks. That maybe, but I felt that with the money I was spending, I didn't want a car I had trouble starting before I even drove it off the lot! I stood my ground and they gave me a different car, but none too happily. I asked if they had a local map for getting out of the airport, and again I got the irritated attitude while she rambled off some very quick directions that I didn't understand. Luckily the car they gave me worked fine, (even though it had over 100,000 miles on it) and I had a nice trip, but I will probably never rent from that company again.
  Your already so exhausted getting off the plane and then to have to do battle with the car rental agency too, it can be such a negative way to begin you time in Ireland.
   And a word about Dublin airport: What a mess! I had a very difficult time navigating around with the construction going on. I found it very difficult to locate the car rental return area.