With almost 40 million albums sold collectively, Jay-Z and Kanye West easily rule hip-hop music. So it's fairly predictable that critics are hailing Watch the Throne, the pair's collaborative album that hit iTunes Monday, as one of the "most historic music events ever." Throne — featuring guest vocals from Jay-Z's wife, Beyonce, and even Otis Redding, who died in 1967 — was first previewed last week at a closed-door listening party at New York's Hayden Planetarium. Just how good is it?

Bow down before Watch the Throne: This "stellar" album is nicely balanced between "hard beats with raw raps" and "risk-free commercial tracks," says Dan Aquilante at the New York Post. The optimistic song "Lift Off," featuring a first-rate chorus by Beyonce, is "destined for radio." Meanwhile, "Otis," a tribute to Redding that has become the album's top-downloaded song, is a "fantastic" way to introduce the soul legend to a younger generation.

"Watch the Throne review: Stellar work from two stars"

But one star outshines the other: That Kanye West is "a hell of a good producer," says Tom Hawkins at Lost in the Sound, is only reinforced by his "slamming" work on Watch the Throne. "Now, if only he didn't rap." His efforts are repeatedly overshadowed by Jay-Z, whose rhymes and verses are "far more competent." Throne, while worthwhile, is the not the classic the world expected.

"Review — Jay-Z and Kanye's Watch the Throne listening party"

Regardless, Throne will change the music industry: In an era when so many albums are leaked prematurely, it's amazing that Watch the Throne was "kept secure from bootleggers," says D.L. Chandler at MTV. Anticipation for the album built steadily, thanks to an "unprecedented effort" to keep it out of the "clutches of hackers," ensuring that it became "one of the biggest and most historic music events ever." Expect other artists to mimic Throne's cleverly, carefully monitored roll-out.

"Watch the Throne released, avoids the big leak"