Trey Parker and Matt Stone have crafted a glorious piece of entertainment. Yeah, it's a Broadway musical comedy in the classic sense...but one from the creators of "South Park". So by definition it's gut busting funny, raunchy and just damn entertaining.
"The Book of Mormon" is simply the next evolutionary step after "South Park: Bigger, Longer & Uncut" and "Team America: World Police" except it's live and in your face.
If you're in NYC and have the opportunity...SEE IT.
As far as geek credibility? Let's just say Middle Earth, A galaxy far far away and the United Federation of Planets are present at mass. I have already said too much.
I'll stop here and let Trey and Matt tell you the rest.