Yeston and Kopit wrote their version first. Webber's was produced first. Yeston and Kopit released their rights to regional theaters first allowing it to be produced around the country.
The Phantom of the Opera was originally a horror story, though both musicals emphasize the tragic romance. When the Phantom's do begin their killing sprees the tones are inconsistent, often promoting as many giggles as gasps.
There was something unwholesome and pathetic about the 1925 Phantom, who scuttled like a rat in the undercellars of the Paris Opera and nourished a hopeless love for Christine. The modern Phantom is more like a perverse Batman with a really neat cave. ~ Roger Ebert on the 2004 Webber Film.
What transpires from this point to the end of the show is a frustrating mix of comedy, spectacle, sentimentality, revelation and suspense, with great highs and great lows. ~ L.A. Times on Yeston and Kopit's Phantom.