I am sure it should turn out fine, its likely that the cake will have a much closer crumb structure, and not be as light and airy as cakes that are made when the butter is creamed with the sugar. It is difficult to get air into the cake mix when using melted butter unless of course you are beating the eggs with the sugar beforehand. Obviously the finished uncooked cake mix will be a lot runnier than it normally would be.
Also using melted butter should make the cake a little more tender, as the melted butter will coat the flour particles inhibiting gluten development, which can cause cakes to be a little tough. Let us know how it turns out if you do decide to go ahead.