It's not a good sign that "Radar," originally featured on last year's Blackout, appears as a bonus track on Britney Spears' sixth studio release—as if she couldn't come up with enough strong new material. Indeed, Circus doesn't match the dance-pop thrills of Blackout, one of the best albums of Spears' career. One wonders if, coming just 13 months after its predecessor, Circus was a bit of a rush job. How else to explain a song like "Mmm Papi"—which is as bad as it sounds—making the cut? Still, Circus has its moments, led by the first single, "Womanizer," already a No. 1 hit. Like a feisty fembot, she struts along the robotic groove. Other highlights include two electronica-infused tracks: the trancey "Unusual You" and the trippy "Blur," which seems to reflect on her party haze.