Essentially, it is currently an automatic "set" and "get" method builder for the member variables you specify. It also has a very basic UMLclass diagram view.
Note that java "rules" are not generally enforced. ( ie you can create an interface with non public methods ). If you are a java developper, I am assuming you have some idea as to what you're doing.
JSkeleton seems to work reasonably well for me. I am not aware of any huge flaws, and I haven't seen it crash and burn, yet, but then again I haven't used it for any large projects yet either.