There's something I can't quite figure out: Why does Rihanna get to be a pop star? And I'm not necessarily asking in a way that demeans Rihanna. I just reviewed her new album, Good Girl Gone Bad, and I was surprised by how much I liked it. In the past, the Rihanna singles I've liked ("Pon De Replay," "S.O.S.") rested on fast and sleek dance-pop tracks that didn't allow her enough space to mangle any R&B runs or to do anything that could be mistaken for emoting, while the singles I haven't liked ("Unfaithful," "Umbrella") slow down the tempos and require her to portray something resembling an actual human being, a task to which she is ill-suited. But the good news on Good Girl Gone Bad is that "Umbrella" is a red herring. Most of the album streamlines her dance-pop even further, to the point where I'm not really certain just what makes Rihanna R&B. The great first half of the album is the sort of shit Kylie Minogue should be doing when she comes back: gleaming, über-produced club-pop that puts all its focus on physical movement and never slows down long enough to toy with petty concerns like recognizable feelings. Even in its slower, prettier moments, like the Ne-Yo duet "Hate That I Love You," it's easier to admire the engineering and craftsmanship than to be sucked in by any story the lyrics might tell. Given that Rihanna's voice is a blank, icy, glass-shattering yowl, this album is actually pretty good — and I'm surprised.