I don't and haven't lived in Northern Ireland, but do have family there.
Personally I couldn't live there because of the weather. I am a southern girl and the temperature and rain depress me. It would be must less of an adjustment if you are currently north of England/Scotland, or indeed if that type of thing doesn't bother you. The upside of the weather is that everywhere is beautiful. And it is less densely populated than much of the rest of the UK, so there is lots of green space generally.
NI has changed massively in the last 15 years. It took a while after the ceasefire, but there has been massive investment and many new shops have opened up. I seem to remember mass excitement in my family that there was finally going to be a John Lewis a couple of years back. Not sure what happened with that one. Don't listen to the opinion of anyone who hasn't been there in, say, the last five years. (And ignore the police stations. Yes, they look scary. They are a hangover).
I do still find that some things take longer to make it to NI compared to our home. However, we are London, so I don't know how much would be the same outside the biggest cities in England too (Bear in mind Belfast is well under a million people, and the whole country under two). Just as a random small example, last time I was there it was front page news (admitedly a slow news day!) in the local paper that baby swimming had opened somewhere. Lots of 'oh my goodness, no arm bands!' stuff. Whereas it is pretty run of the mill here. I am not saying it's a bad thing or anything, just a potential adjustment if you are currently somewhere like Manchester, London or Birmingham.
The culture is very much more northern/small village than the anonymity of a large city in the south of England. I find the fact that everyone wants to know my business a bit oppressive, but I am a grumpy Londoner and plenty of other people just feel that it's a lovely friendly place to live.
Overall, if you can live with the weather, I think you'll like it. And you can buy Tatyo crisps, which is a major plus!