John Mayer — what a curious case. As a pop personality, the guy's a barrel of laughs. He's a tabloid fixture who wears his celebrity with a wink: modeling Borat's onesie swimsuit, starring in goofy YouTube videos, and generally disarming, with wit and self-deprecation, the millions inclined to hate a starlet-shagging guitar virtuoso. But then Mayer steps into a studio, and the fun spigot claps shut. It's as if Mayer, burdened by his status as heir apparent to the Clapton-Sting-Knopfler tradition of classy pop-rock classicism, pulls on a mask: the Furrowed Middlebrow.

Video: John Mayer on the "Vulgar Relationship" Behind his New LP

There's no doubting the man's chops. Battle Studies is a real study in craftsmanship and understated guitar ninja-dom, and musos will thrill to Mayer's deconstruction of Robert Johnson's "Crossroads." But the solemnity is suffocating. On "Heartbreak Warfare," Mayer delivers U2-style guitar and strained war metaphors: "Clouds of sulfur in the air/Bombs are falling everywhere." That bust-up with Jennifer Aniston was bad, but was it really like the firebombing of Tokyo?

Battle Studies is terrific when Mayer drops the seriousness, pondering and sending up his reputation as a rake. On "Half of My Heart," with Taylor Swift, Mayer plays the dude who kisses with one eye open, scanning for his next conquest. Then there's the folk-pop single "Who Says," the confession of a dope-smoking roué: "I don't remember you looking any better/But then again, I don't remember you." Turns out, loose, louche, funny Mayer isn't just good for publicity. It's good for art.