We saw it last Nov. and loved it. I would say 1-2 hrs should be plenty. It's so cold in there that even though you want to linger longer, you just can't. I'm from the NE so I thought I'd be able to hang in there but the coats were thin and just didn't feel like enough.
They did give coupons for free hot chocolate but it was in a different part of the hotel and we were so tired from flying in that afternoon, we decided to skip it.