I found out about Ireland when I went there to work for a couple of weeks as a motorcycle instructor/tour guide about 15 years ago. Been back many times since. Once on a 3 week tour of the whole coast line with the wife.
I found Northern Ireland to be a scary and unpleasant/unwelcoming place. On one occasion the wife and I wandering around the seaside town of Carrickfergus just north of Belfast went into a pub with a huge Union Jack flag draped over it's front, we sat down at a corner table with a drink at a corner table and the barman came over with a cloth "to clean the table" leaning over speaking quietly out of the corner of his mouth he said, "just a friendly warning like but I wouldn't stay here if I were you". We didn't. Londonderry is the scariest place I've ever been, totally intimidating.
Southern Ireland on the other hand totally different; the first time I ever went to Ireland I had to meet a man in a bar in Limerick (not wanting to be late I got there very early), it was one of those large marvellous pubs you get so many of in Ireland, stained glass windows, crystal chandeliers, large brass foot rail at the bar. I ordered a pint and stood at the end of the bar. Within seconds a rather scruffy farmer type detached himself from a nearby group and came up to me and speaking in a very broad accent said, "your not from round here are you". No I'm from England just over for work. "Well don't stand here by yourself come and talk to us". I thought he was trying to scrounge a drink or something but no he insisted on paying for mine and was just being friendly. Typical of the attitude I found all over the south where God knows they have every reason to hate the English unlike the north where they want to be English (allegedly).
Favourite place/top tip to visit.... Dingle where it seems every other building is a pub and has live music.... I could live there.