Well it's hard to say because it depends on what teacher you get. I happened to get a teacher in game design that was really good at teaching us to be creative and come up with ideas ourselves which I think has been really helpful and made us see games & game design in another way. I do however think that being self taught can be just as good, but an education could at least give a little boost and be a great way to get you started (as that is the hardest part for a lot of people, which it was for me).