Now to summarize my thoughts on hedonistic theories of welfare (understood broadly, to include qualia preferentism and other views on which your welfare depends only on your subjective mental states)...
(1) Some people are drawn to welfare hedonism for largely linguistic reasons: it just sounds wrong to their ears to say that a person is 'harmed' by an event that doesn't impact their experiences. In at least some cases this is the result of demonstrable conceptual and metaphysical confusions -- e.g. conflating different senses in which one might be "affected" by an event. But in any case, there is little point getting hung up on terminology. As I argue in 'The Importance of Implications', we should instead focus on the substantive normative questions in the vicinity, e.g., what we should want for the people we care about.
(2) When we reflect on the things that really matter to us in life, most of us find that we care about much more than just the quality of our subjective experiences. We also want, among other things, to form meaningful connections with other people, and to make actual progress towards accomplishing our goals. A life of pleasant delusion does not seem nearly so appealing. The hedonist may suggest that this is just because we care about more than our own well-being: for example, we want others to be well-off even when this doesn't benefit us personally. But even bracketing such moral concerns, departing your current life for the superficial thrills of Nozick's experience machine doesn't even seem like something worth doing for your own sake. (For another example: nor does plugging Morpheus back into the Matrix against his will seem like a particularly benevolent thing to do.) For many of us, at least, a life of appealing experiences is not sufficient for an appealing life.
(3) Some hedonists try to debunk all such preferences as having been 'corrupted' by our mentally 'perceiving' what were meant to be unperceived events. I address this objection in my recent post, 'Imagining the Unseen'.
(4) Ben Bradley argues for hedonism on the grounds that other views run into problems specifying the 'timing' of certain harms. 'Must harms be temporally located?' explains why this is unconvincing.
As noted in #2 above, hedonism makes some incredibly implausible claims. For any hedonists out there: what do you think should motivate us to accept them nonetheless? (Even if you find that you personally only care about the experiential aspect of your life, what's the motivation for overriding others' self-regarding preferences regarding the sort of life they want - on reflection - to live?)