He's not a rap man, he's an app, man. The drop of Jay Z's new album "Magna Carta …Holy Grail" at midnight on Independence Day seemed less like a musical event than a Silicon Valley IPO. Conveyed exclusively by a Samsung application to a million Galaxy phone and tablet users, the release not only forced old-media institutions to rewrite their rules and raised complaints about NSA-style invasions of privacy, but came with a glitch that crashed the promised downloads.

Rubbing out the boundary between art and entrepreneurship always has been part of Jay Z's hustle. But now that some of the pixelated fog has dissipated and we've had time to listen to the album, how does the music measure up? For a creator who crows, "Oh, I'm so good at math," Jay's made a product that's less than the sum of its impressive surfaces.

The production, by Timbaland, Pharrell Williams, The-Dream, Hit-Boy and others, gleams like the luxury good it is. But the music is only intermittently moving to head, hips or heart. The most enticing sonics, like the New Orleans horns on "Somewhereinamerica," seldom coincide with the freshest bars — even if "Somewhere in America, Miley Cyrus is still twerkin' " rivals Kanye West's "Hurry up with my damn croissants!" as 2013's funniest cross-cultural-double-dutch twist.

While Mr. Carter's status as an Old Master of rapping is not in doubt, the "old" side of that equation weighs heavier and Hovier. His sights never quite lock in. The multilevel wordplay, wit and wisdom that are his calling cards flicker amid the Fortune 500 asset inventories and street-cred callbacks, and punch lines that often warrant the lamentable tag of Dad Rap.

In the artist's defense, there aren't many rappers who've survived long enough, physically, psychologically or commercially, to grapple with aging with dignity. His star has risen right off the road map, as was bound to happen to someone in the genre's fourth decade. But a few extra features engineered into the Magna Carta app would have helped.