I'm not exactly from Belfast, but my mother is (near Cregah road) and we lived there for a year or two when I was a child (9/10) and made regular visits to grandparents, uncles aunties and cousins. I've been back a couple times as an adult too.

Belfast is great, although it does definately help to have a local contact. The people are generally friendly, and love tourists, just don't say any dumb Irish-American crap about the Troubles.

I had much more fun being a tourist there than in Dublin on my last visit (in both cases I was staying with friends of the family).