"Under the Mistletoe" isn't just Justin Bieber's first Christmas album. More significantly, maybe. it's his first album as a baritone.

Well, relative baritone. The kid is still capable of sounding like he's singing in his falsetto range even when he isn't. But from the first not-so-stratospheric notes of "Only Thing I Ever Get for Christmas," it's clear Bieber has been through the non-menopausal version of The Change.

Or, to put it another way, "vocally, his balls have dropped," as his manager Scooter Braun was quoted as saying this past week, accurately, if indelicately.

For comparison's sake, proceed directly to the vintage track that closes the album's deluxe edition, a cover of Donny Hathaway's "Someday at Christmas" that appears to feature the same vocal Bieber put up on YouTube back in 2007. It sounds like an outtake from "The Chipmunks' Christmas Album."

But he's no cheerful, squeaky-voiced rodent on the newly minted tracks, even if it's a bit premature to certify the 17-year-old cougar-chaser (sorry, Selena) as a full-fledged soul man.

A who's who of R&B guest stars (and one country star) offer a holiday assist. His mentor, Usher, helps roast the chestnuts on the world's 15-millionth unnecessary reprise of Mel Torme's "Christmas Song." Boyz II Men -- speaking of boys becoming men -- collectively help out on an original, "Fa La La," singing that they "wanna be your biggest gift."

Mariah Carey guests on a re-do of her own "All I Want for Christmas" (the '90s smash that history may record as the final original Christmas song ever to become a standard). But it seems more appropriate to say that he guests on her recording. Bieber cut the song in a lower range, but then Carey heard it and suggested that they should do it as a duet, provided that he bring it back up to her original key. He should have kept the first version and turned her down; the end result sounds like Bieber singing along with Carey karaoke.

Certain to be the most polarizing track: "Drummer Boy," where both Bieber and Busta Rhymes add topical, lickety-split rap verses to the familiar tale of Jesus' own percussionist. Bieber also plays (yes) drums on the cut. To most non-fans, it'll sound like coal squared, but this "Drummer Boy" is so brash in its dumbness that it's kind of likable.

"I only spit heat 'cause I'm playin' for the son," Bieber raps, in one of the album's stranger juxtapositions of the sacred and secular. "I'm surprised you didn't hear this in the Bible/I'm so tight, I might go psycho/Christmas time so here's a recital/I'm so bad like Michael." (Michael Jackson as honorary Christ child?)

But Rhymes gets the prize for best couplet in "Drummer Boy," as the veteran rapper actually manages to rhyme "all our Twitter followers" with "happy Hanukkah." Now, that's Christmas chutzpah.

This may be the first adaptation of "Little Drummer Boy" to include a mention of mistletoe, a plant not previously mentioned in any extra-biblical accounts of the gift of the Magi. But the title of the album is "Under the Mistletoe," and Bieber manages to make mention of it in almost every track on the album.

It's really a concept album, then, this is -- not just in the way that every Christmas record is a concept album, but a collection of songs specifically themed around an "obligate hemi-parasitic plant" (thanks for that, Wikipedia).

"I should be playing in the winter snow/But I'mma be under the mistletoe/Shorty, with you," he warbles in the quasi-reggae-styled title track, already a hit single. "The mistletoe can pull us closer...?It sorta feels like it's Valentine's," he sings in "Christmas Eve," a seductive lothario's anthem co-written with Chris Brown. (Presumably Brown is the one responsible for the lascivious-sounding line: "You leave some cookies out, I'mma eat them all.")

The word mistletoe pops up in such a ridiculous plurality of the songs -- originals and covers alike -- that it's a little surprising when Bieber finally gets to "Silent Night" and doesn't add a line about wanting to make out beneath the stuff behind the stable.

You have to give Bieber and crew credit for loading the album with so many newly written songs, when most celebrity Christmas carolers are content to go after a quick cash-in by spending a day or two in the studio rushing through Bing-approved oldies.

Then again, not much original thought went into the new songs, which mostly consist of tangled combinations of Christmas cliches. To wit: ""I'll deck your heart with boughs of holly/Baby 'cause you're the reason to be jolly"… or "Baby I will not pout/Baby I will not cry/'Cause I got your love this Christmas time." You get the picture, even without opening all the flaps on this particular chocolate advent calendar.

There are some lost opportunities here. The most unusual guest, the Band Perry's Kimberly Perry, duets with Bieber on "Home This Christmas," but it's such a generic ballad that Perry's wonderful rasp is wiped clean, leaving the country singer sounding like just another pop session chick.

Perhaps the album's most novel idea arrives with "Santa Claus is Coming to Town." No, he doesn't sing the often-copied Jackson 5 arrangement of the tune, as you'd expect. Instead, Bieber hews to the traditional melody but then sets it against an instrumental backing that pays as much homage to "I Want You Back" as humanly and musically possible without having to pay royalties. That subtler tribute is a clever, if slightly bizarre, way of bearing gifts for the late King of Pop.

Will "Under the Mistletoe" be huge? Of course. What chance does it stand of being pulled out as a perennial 10 Christmases from now? About the same odds that Frosty has of celebrating Memorial Day.