This was the second half of a family vacation.
The apartment was big, well-decorated, and had all the amenities that we would need for several nights in Belfast. Location is pretty fantastic - we were within walking distance to much of the central Belfast city core. There is parking on site included.
Problems:
1: You can only get help between 9am and 5pm. If you arrive after 5pm, and have issues getting the garage door open like I did, you're out of luck until the next morning (note that standing to the left of the door and pressing the button repeatedly will work eventually). Similarly, if you find out that the smoke detector in the room is complaining of a dying battery, there's no one to help until you've spent a night with non-stop beeping.
They did respond quickly the next morning, and dispatched a maintenance person to look, but they weren't equipped to fix the problem, and we never heard from them again. It beeped our entire stay.
You also have one set of physical keys to worry about. Go to a pub and forget/lose the keys? You can't get back into the room until morning. They should be offering a spare set.
Yes, this is a short-term rental type property. Others I've stayed at had a number to call at any time.
2: It simply isn't comfortable. The beds were top 3 worst beds of all my hotel stays in Europe. Couch wasn't better. The rooms make for nice Instagram pics, but that's it.
I'll return to Belfast. But not this apartment.