That is one creepy Joker! That face is going to decay before he gets it back on.
@slopoke36: It is made to make add to the creepy effect,and it worked.
It is used to add the dark feel to the story,but I think your asking,"what happens when the story is done?"
Of course that won't be his permanent face,maybe he will have it sewn on,or it will heal in,plastic surgery (he's had it before),etc.
Nobody knows.I like it,it adds strongly to the story,without changing the character (in a bad way),I am tired of the old joker who was always doing the same old crap,he was less than deadly,he was pathetic and slightly threatening in most cases.most.
Don't expect it to last forever,which is another good thing,I would prefer if it wasn't permanent,but it most likely isn't since this is a story arc.
I mean,they change joker's face in arkham city and in situations that are like that,yet nobody complains.Especially since he has a deadly disease,of course he isn't going to look like the pasty-white clown wearing lipstick.