I also use one these ball type compasses while I am hunting.
Johnny is right in that it is easy to just look down to get a fix on a general direction with it when you are pushing through heavy bush.
I pin this ball compass on my left shoulder and it also prevents my rifle sling from falling off my shoulder when moving.
I have a Timex Compass Watch but have not found it very reliable (it always seems to need resetting) so I replaced the original watchband with one that has a buttom compass built in to it. I got the plastic replacement band at WalMart for about $4.00.
Mike