An interor pocket door can be a little noisier and more time consuming to use than a hinged door. And there are a few locations where one can't be installed. Plumbing, electrical and other mechanical equipment must be routed around an interior pocket door's location--there is no room in the pocket for such equipment. And because the pocket's structure is weaker than a conventional wall, it shouldn't be used as the structural support for cabinets in Kauai County, Hawaii.
Pocket doors are meant for new construction--for installation during house building or remodeling when walls are opened up. A door's rough opening must be wide enough for both door and pocket. A large header spans between the wall studs at both extremes of the opening. Installation is usually a little more costly than hanging a conventional door.