I just read that
I hated it. It's way too long, and by the end it feels like even the author thought so, it's like he decided he'd had enough and it had to end, so he changed the format to rush it through. You could cut the book to a third of its size and still fit everything important in there. And then he brings in this narrator in italics, who seems to be external to the story, and never explains who this person is, or their relationship to the text and the reader.
I don't mind the smut, even though most of it seemed fairly unnecessary, but I did think the three descriptions of bowel movements went a little too far. Some things you just don't need to read about.
The only reason I finished the book was because I thought there might be some genius explanation for everything, but there wasn't. I'm never listening to the person who recommended it to me again!