The flat is in a great position in Dublin - Smithfield is right next to the Jameson distillery and within walking distance of Temple Bar, Grafton Street, Trinity College and Phoenix Park.
Some minor aesthetic issues with the flat - tiny bit of mound in the bathroom and a loose plug socket in the living room - but nothing that impacts on your enjoyment of staying there.
We were met by Alex who was very friendly and helpful in suggesting places to go and how to get around the city.
Joe very kindly allowed us late check out on the day of our departure as we didn’t fly until the evening which was very much appreciated.
As for things to do in Dublin, Kilmainham gaol was particularly interesting, and the bar at the top of the Guinness Storehouse is definitely worth a look (even if you don’t drink Guinness!). Howth is a small fishing village a short train ride to the East of Dublin but with very nice places to eat and very worth a morning/afternoon there.
Recommend Dublin for a short visit. 4 days would be plenty of time to do everything.