A good review article on the current state of our knowledge, focussing on the entire spectrum of sexual enjoyment and not just erectile function. They make clear that the enjoyment of sex is a product of many factors, including pre-ADT sexual function, habitual sex frequency, testosterone (amounts needed vary widely), erectile function, partner enthusiasm, sexual aid use, non-penetrative intimacy, physical fitness, sleep, masculine self-image, depression, and novelty.
It is worth noting that Richard Wassersug is one of the most cited researchers on these issues. I hope he will comment.
(If you create a free sign-in, you should get free access for a couple of months. If that doesn't work, see Dr. Wassersug's post below.)