Those who have come to regard "boy bands" merely as jibe-targets likely aren't surprised that they've proved more resilient than interesting or worthwhile. Still, Backstreet Boys sound particularly confused on Unbreakable. The first source of their confusion seems to be how much, exactly, they want to sound like Maroon 5: Songs like "Everything But Mine" and "Any Other Way" traffic in clips of funk guitar that make the comparison hard to ignore, and no amount of live instrumentation plays to Backstreet Boys' strengths in terms of harmonies and hooks—those things that serve "hits" more than "songs." The second source of their confusion is why, exactly, they chose to make another album after so many years away. A few songs, including the single "Inconsolable," reach the stirring heights of old while maintaining Backstreet Boys' habit of mimicking, melodically and structurally, songs by Def Leppard. But those heights prove fleeting on an album that lacks both a mission statement and a sense of purpose.