This was PERFECT stay for us as we traveled around the west of Ireland. Everything was great. Even though they don't have their own car park (aka parking lot), there's a municipal one across the street for only 2 Euro.
I do want to note that our room did not have an air conditioner. There was a fan in the closet, so I'm pretty sure that's accurate. If you travel there in the summer, and it's hot, you want to be prepared for that - especially for Americans expecting every place to have AC.
We will DEFINITELY be going back to Westport and staying at The Mariner again.