Swapping a standard bedroom door for a sliding barn door instantly frees up floor space and makes the whole room feel finished. Once it is in, you stop tripping over a swinging arc and get a cleaner look every time you walk past. A basic install takes a couple of hours if you are handy, or half a day if you are measuring twice to hit wall studs.
Home stores usually run their best clearance deals in late winter and late summer, which is the time to shop. If you are hiring someone to hang it, get at least three quotes so you know what the going rate actually is.
That intro window is a firm deadline, not free money, so make sure you pay off the full balance before the 15 months run out or interest will kick in on what is left.