The 53-minute album--which sounds a bit dated, but will be a joy for previous Backstreet Boys fans--kicks off with a short harmonic intro, led by A.J. McLean, that ably showcases each of the remaining members' talents.

True to the group's past, the songs on "Unbreakable" are instantly memorable. "Inconsolable" and the power ballad "Something That I Already Know" are classic Backstreet Boys, with soaring vocals and simple, real instrumentation cascading beneath their rich harmonies.

"Inconsolable," the album's first single, was penned by Emanuel Kiriakou, the man behind Nick Lachey's solo hit "What's Left of Me," explaining the parallels between the two songs. "Something That I Already Know" is a mid-tempo tune that could serve as the follow-up to "Inconsolable," with the lyrics advising listeners how to move on from a rocky relationship.

The group--which also includes Nick Carter, Brian Littrell and Howie Dorough--even strays outside of its comfort zone on a number of tracks. "Everything But Mine" features a dizzying, distorted vocal over a twinkling Europop beat. The club-ready, 4-minute song wouldn't be bad if it was cut in half. "Any Other Way" kicks off with a blistering--that is, "blistering" in terms of boy-band ilk--guitar solo and segues into a bouncy beat. The verses of "One in a Million" fall flat, but the song is resurrected through the desperate chorus, "I wish I could tell her/she's one in a million."

The sequencing of the CD is interesting. Kicking off with the aforementioned intro, the album tiptoes through the Backstreet Boys' history, and gets more mature as it progresses. The piano-laden "You Can Let Go" could easily be found on adult contemporary radio. "Trouble Is" is almost bluesy in its delivery. "Treat Me Right" musically resembles the P. Diddy/Keyshia Cole collaboration "Last Night."