Ok, the bag fills up fast, but then that's because the system does such a terrific job. One bag lasted two weeks, but then the cleaner itself  gives an indication when the area is still dirty, so you tend to be more careful in vacuuming. Bag replacement is a bit clumsy but no more so than most machines.  I had no trouble removing the bag and not spilling its contents. Yes, you have to fold the top and bottom over when you install it but that's because it unfolds when it fills up.  Expense? Most vacuum cleaner bags are too expensive.