"One dimension of emotional capacity that we can imagine enhanced is subjective wellbeing and its various flavors: joy, comfort, sensual pleasures, fun, positive interest, and excitement. Hedonists claim that pleasure is the only intrinsic good, but one need not be a hedonist to appreciate pleasure as one important component of the good. The difference between a bleak, cold, horrid, painful world and one that is teeming with fun and exciting opportunities, full of delightful quirks and lovely sensations, is often simply a difference in the hedonic tone of the observer. Much depends on that one parameter.
It is an interesting question how much subjective wellbeing could be enhanced without sacrificing other capacities that we may value. For human beings as we are currently constituted, there is perhaps an upper limit to the degree of subjective wellbeing that we can experience without succumbing to mania or some other mental unbalance that would prevent us from fully engaging with the world if the state were indefinitely prolonged. But it might be possible for differently constituted minds to have experiences more blissful than those that humans are capable of without thereby impairing their ability to respond adequately to their surroundings. Maybe for such beings, gradients of pleasure could play a role analogous to that which the scale ranging between pleasure and pain has for us. When thinking the possibility of posthumanly happy beings, and their psychological properties, one must abstract from contingent features of the human psyche. An experience that would consume us might perhaps be merely “spicy” to a posthuman mind.
It is not necessary here to take a firm stand on whether posthuman levels of pleasure are possible, or even on whether posthuman emotional capacities more generally are possible. But we can be confident that, at least, there is vast scope for improvements for most of individuals in these dimensions because even within the range instantiated by currently exiting humans, there are levels of emotional capacities and degrees of subjective wellbeing that, for most of us, are practically unattainable to the point of exceeding our dreams. The fact that such improvements are eagerly sought by many suggests that if posthuman levels were possible, they too would be viewed as highly attractive."
– Nick Bostrom in The Transhumanist Reader: Classical and Contemporary Essays on the Science, Technology, and Philosophy of the Human Future