Finally got around to watching this ... WHILE ON DRUGS
The last hour or so can fuck off. Before that I was really liking it a lot. I definitely agree that the drawn out parts were really integral to the experience.

But by the end I felt like the visuals really dropped off and became so fake that I wasn't really interested any more. And the whole in-vagina/first-person-sperm thing was very "WE GET IT."
I guess it didn't help that I watched the 161 minute version either.