Someday, when Miley Cyrus is shaving her head and entering rehab, we'll hear her cover of "Girls Just Wanna Have Fun" as a cry for help. But Billy Ray's little girl is under a very different pressure: namely, to not be Britney. For someone who's meant to embody America's wholesome ideal of teendom, then, Miley's proper debut is pretty adult. Not in a Vanity Fair sense as much as just an undue focus on hard breakups and serious relationships. Except on the tween-tastic title track and the sassy "Fly on the Wall," Miley doesn't sound like she's having much fun.