I've owned one since release and the only time it's even felt warm to the touch is after charging from a low battery. I'm also not running renders or such on them, they're not really designed for that.

No ventilation means more thermal mass in the place of airways to absorb and disperse heat. I specifically bought this model because I am tired of fans in my laptops, which have failed multiple times or become loud to the point that I couldn't even have it in a meeting room without it being a major distraction. Perfect, guaranteed silence at all times from my electronics is a beautiful thing.