I'd been looking for this at Bongo for a while (I kept thinking it should be on the new release shelf long after it became a 'regular' movie), and finally picked it up and watched it last week.
Joseph Gordon Levitt is amazing in it. His character is a hustler in a small town - his clientele are exclusively older men, just like the man that sexually abused him the summer he was 8. He is hailed as beautiful and exquisite by his johns, and he does have a beatific look on his face at some key moments.
There are several depictions of the abuse, and the character talks about how much he liked being so special to the man, his baseball coach.
In looking for reviews, I found this, which has three short reviews. In one, the reviewer talks about the "soft focus" look at pedophilia, and Mysterious Skin does have that feel in parts. It is very uncomfortable to watch that, and there is one particular scene later in the film that made me flinch. Sexual violence is yucky. But it seems pretty real too (I don't have first hand knowledge of how these people operate, or what a relationship with an abuser could be like).
I liked it, and I will watch it again. But probably not for a long while.