An in the waist band (IWB) holster makes it more convenient to hide the holster and gun since the outside the waistband holster hang down below the belt line. Some of the difficulties with an in the waistband holster are the bulge it causes and also some of the same problems associated with the belt holster.
Using a Public Restroom
I have found it is just as difficult to use the restroom with an IWB holster as it is with a belt holster. There still has to be a place to remove the gun and lay it so that you can use the restroom. Also, you need a private stall. the good part about the IWB holster over the belt holster is the IWB doesn’t flip over if you try to leave your gun in it as bad as the belt holster does.
One problem with the IWB holster is the bulge in the pants. If a person wears tight pants, mine are, then a new pair of pants a size larger is needed. This creates another problem because larger pants are not just larger in the waist band, they are larger everywhere and become bulky.