I lived in Belfast for a couple of years (I grew up in North East England but have lived all over the place, mainly for work reasons - no, I'm not in the armed forces, there just isn't much work in the north east for what I do and when people get into good jobs they stay in them. For decades.).
The following is based on my experience, so I'm going to apologise in advance to anyone I might offend. (I spent my first four months in Belfast basically smiling and nodding, I was so paranoid about having an English accent. I didn't need to be, it was just my perception. Besides which Geordie shares a LOT of words with Northern Ireland...)
The whole two years I lived there though I did feel as if I had to be quite careful about what opinions I expressed. Again, it could have just been my perception, but friends and relatives who visited said the same, and many of them had connections with the locale.
The good things about Norn Iron: the landscape; the sheer amount of space; the cost of living. Your money will go a LONG way, not just in terms of housing. (Though food and utilities are still about the same price, there is no council tax and water may well be in with the rates. I rented, so I paid separately, but I loved not having to pay council tax.) There are some lovely things to do, especially in Belfast (I can't really speak for anywhere else). The coastline, the countryside, the woods - they are all really stunning, and a lot of money has been put into the river side part of Belfast too. Air links are also surprisingly good. And St George's Market is a great place to spend a Sunday morning, whether you're local or visiting. The hiking is great. The Mournes are beautiful. The northern hills are stunning. And a lot of the time you have them more or less to yourself. Much of Northern Ireland is at least as beautiful as Scotland, but so much less well-known.
The produce. Just about all of it. The beef is good, the dairy is good, the chicken is excellent, at the coast the fish is really fresh, the fruit and veg are good, the apples in Armagh are especially good (one of the people I worked with had a farm where the apples were used by one of the BIG cider companies in England for their products, they were that good), Comber potatoes are lovely. And parts of Northern Ireland, as well as being AONBs, have something of a microclimate, so I saw plants thriving there that I've only otherwise really seen in Cornwall.
The things I struggled with in Norn Iron are below.
I found Belfast surprisingly cliquey for such a reasonable sized city though that could just have been the utterly nutty organisation I worked for. It has something of a reputation. Plus my boss was insane and thought one person could accomplish the work of three people. Plus THEIR boss was insane and addicted to meetings and winning awards. Plus the entire department was full of, er, characters. I'm not kidding. One day I will write a book. 
The traffic. Once you're outside Belfast it's a pleasure to drive most places most of the time, but in Belfast itself the road planners must have been on something when they designed the centre. I'm not kidding. It's bonkers. Sales reps who visited us said exactly the same.
On the topic of transport, the ferries are extortionate. However you do it, even if you come in through Dublin or Waterford and then drive up. And I know BJ has started muttering about building bridges from Scotland to Northern Ireland; after all, generations of engineers couldn't possibly know better, eh...Parking in some parts of Belfast city centre will require you to take out a second mortgage although there are places here and there that are cheap. Oh, and the buses are a bit erratic. And colleagues who came in to work by train were regularly late due to bomb scares. Yes, they still happen. Regularly. Car-jackings also happen occasionally (though to be fair, they happen in England too).
The sectarianism has not gone away. As an English woman I stood outside it to some extent but I was also quite isolated since I didn't belong to any denomination. As an observer, it seemed to me that religion was still much more important than in England.
With regards to shopping and eating out, don't expect to find much open on a Sunday morning until at least noon (although shops stay open from noon until 6pm on Sundays usually). Oh, and lots of museums etc close on a Monday though I think that applies in England now as well.
The weather. It gets cold. Like, properly cold. And properly, properly wet. Together. Most of the year. Friends visited in May and I took them to the Causeway. I think we each had five layers on at one point including woollen scarves, gloves and hats. Might even have been six....
If you are used to a London lifestyle you will find Belfast very, very different although even in the couple of years I was there I saw masses more restaurants open and the shows put on at the theatre and the big arena got much more diverse. It started getting much easier to get, say, Asian food although who knows how Brexit might affect things...
On the subject of diversity, Northern Ireland is still mainly Caucasian, outside a few areas.
If you buy anything online you will almost always have to pay extra shipping and it will be at least a day later than you'd get it in England; some companies won't deliver to Northern Ireland at all. Bear in mind that pretty much everything except some food has to be brought across by ferry.
Education is still mainly segregated unless you go private, although the quality of the state education is generally much, much higher than in England. I also know there have really been issues with recruiting healthcare staff (my job involved liaising with the NHS) so you really might want to look at that if you decide to move there.
The politicians. Pretty much all of them. If you think English politics are bad, bear in mind that Northern Ireland didn't HAVE a parliament for three years (was it three years? I lost count. A long time, anyway).
To the day I left I was a blow-in. (I only discovered after I left that I had an Irish great-great-grandfather who was a linen worker, and given where he moved to, it's fairly likely he was from Ulster. This might have helped a little as one of the reasons the people I worked with found acceptable for moving to Northern Ireland was if there was a family connection of some kind.)
If you do decide to move, all the best though. Just bear in mind it is a different Home Nation.