P ioneered in the U.K., the format is now available worldwide. The drawback to these courses is that you're on your own, so you must be very self-disciplined and highly motivated.
Tutorial support is usually available by fax or Internet.
You also don't have as much access to or ease in forming networks with your fellow students - another reason people go to business school. These types of courses rely on specialized books, audio and video tapes or CD-ROMs.