Dublin is a nice city and is the capital of Ireland, it's one of my favourites cities because I was there last year on my students trip and I enjoyed a lot of.
If you like have a great time walking, this city has a lot of beautiful parks like St. Stephens Green. You can enjoy too going shopping in O'connell and Grafton Street. Also you can visit the Guinness Store house and learn the process of beer, there is the gravitty bar where you can see amazings views of all the city. If you like nightlife you will enjoy visiting Temple bar, there are a lot of pubs and restaurants. You have to visit too the trinity college university, that is the older university of Ireland.
If you are looking for a nice city to enjoy then you´ll love Dublin.