Katy Perry: 'Part of Me'

Katy Perry's back on Idol, singing her latest hit, Part of Me (probably my favorite song of hers since Firework). She keeps the Marine theme from the music video, dropping in from the ceiling along with her dancers, like they're coming down from helicopters. It's a pretty impressive production, which is good, 'cause Katy's always a bit limited, vocally, and tonight's no exception. She's helped a...