It seems the experience machine's design would be a rather important thing to be described prior to asking the question. Let us suppose, to bolster Nozick's argument, that the machine is set to deliver maximum, unending pleasure (and not merely a matrix style Tahitian beach, or whatever barely improved setting people generally conceptualize as paradise).
Such a machine would necessarily capture 100% of the subject's attention, of the subject's consciousness, 100% of the time, drowning the mere possibility of thoughts in a flood of stimuli.
This is a situation we normally find ourselves in only briefly, in fleeting and rare moments of ecstasy (and these moments may not be as intense as what is being produced by the machine). Making it a permanent fixture of our experience of life necessarily comes at the expense of all others.
Pleasure or pain. Pleasure or curiosity. Pleasure or nostalgia. Pleasure or love. Pleasure or thought.
A human being incapable of experiencing anything else (the machine rendering the relevant neuronal clusters useless and idle) can hardly be called human. A human being ceasing to be a human being can hardly be called the same person.
The loss of personal identity is in our view reason enough to refuse stepping into a machine designed as per the above. Something else will benefit from the experience, hence the whole enterprise is pointless (if removed from the machine after some time) or worse, akin to suicide (if the arrangement becomes permanent - or hinges on the subject choosing to leave it, which is nothing short of impossible once turned on).
Such an experience machine cannot be designed to serve humans. A matrix style virtual reality machine on the other hand can be wholly compatible, and is indeed preferable to unedited reality.
Note: there is here the very real possibility for a slippery slope, starting from barely improved reality and gradually morphing into the experience machine. The point at which personal identity ceases to continue is of course arbitrary, and may subjectively not matter anyway depending on the pace of change.