It's been interesting to watch Over the Rhine's stylistic evolution over the 20 years since Till We Have Faces, their debut album: their sound wasn't far removed from the American heartland to begin with, but these days it's getting close to Tom Waits territory, what with the barely-in-tune pianos, the mandolins, the slide guitars, the humid-summer-evening tempos, and Karin Bergquist's increasingly smeary approach to sung pitch. There's also more than a touch of Lucinda Williams in her grainy vocal tone and her slushy consonants -- which are nearly nonexistent on "Rave On" -- and when Williams herself makes a cameo appearance on "Undamned" you may not even notice her. Then there are the lyrics: Bergquist's tend to be evocatively minimalist and impressionistic ("Rave On,") while those written by Linford Detweiler, her husband and musical partner, tend to be discursive and rambling ("Undamned," "Infamous Love Song"), and tend to address more directly the religious themes that used to be more prominent in Over the Rhine's songs than they are now. There are times when the early-Americana theme starts feeling a bit heavy-handed, such as on the torchy "Infamous Love Song," which sounds kind of like a Kurt Weill outtake and the melody of which owes a bit too much to "Brother, Can You Spare a Dime?" But more often their approach balances old, new, and whimsical perfectly: "Only God Can Save Us Now" has a lightness at its heart that is belied by both its title and its madhouse lyrics,