The Pick of Destiny is often hard to resist because Gass and Black are playing such amiably clueless losers. But for the real-life performers, satirizing stupidity is a dubious achievement we'd like to see them outgrow.
Jack Black's constant mugging and eyebrow wriggling reaches an obnoxious new low in the awkwardly titled Tenacious D in the Pick of Destiny. He is brash and loud, as his pupils bounce around their sockets like pinballs.
My advice: set aside the money you would have spent on a ticket toward buying the soundtrack. That way, you can get all that's moderately good about Tenacious D in the Pick of Destiny without having to endure the substantial bad.
The plot pings along energetically, and if it rarely makes much sense, it usually finds the shortest distance between two jokes. Like a dumb but infectious rock song, you can't really justify loving the movie for any serious reason.