Joffreys been getting worse and worse since he took the throne, its hardly sudden. This week just showed that he's more than just spoilt, he has genuinely sadistic tendencies that would be there regardless of his up bringing and position. Don't forget he's inbred, I think he's lacking a bit in the brain department.
As for the smoke monster, I'm reserving judgement. Effects were certainly a million times better than Lost.
