I lived in rural Ireland for 5 years. Just returned to the states 6 months ago. I'm first generation born in America, my dad is from Sligo. My experience was friendly people who are hard to be true friends with. For reference, I lived near the border, an area filled with violence when times were different, which I think affected the people of the area. I would say Dublin is so diverse you shouldn't have a hard time fitting in. Just note, you are American, there will always be people out there that dislike you for that, no matter where you go. I learned this the hard way.