Xtina goes X-Rated on her fourth full length album. Boasting collaborations with the likes of M.I.A. And Peaches, 'Bionic' has a modern electronic sound that lives up to its title. Its overtly sexual subject matter is often needlessly risqué, but it's packed with enough heavy beats and catchy hooks to get you shaking those hips on the dancefloor.

The notion that Christina Aguilera has been copying Lady Gaga with her recent antics (including an S&M themed video for 'Not Myself Tonight') seems rather hilarious when you consider that Xtina was causing scandal with sexually explicit lyricism and the purposely shocking music video for 'Dirrty' all the way back in 2002. On those grounds at least, let's assume that Ms. Aguilera is hanging up her 1950s do in favour of futuristic exhibitionism for her own reasons, rather than to compete with the likes of Gaga and Rihanna. As if she'd need to with a voice like that.

'Bionic' really is explicit, though, and it rightly sees Christina labelled with her first ever parental advisory warning. After all, few parents will want to hear their kids singing along to lines like "All the boys think it's cake when they taste my (Woo Hoo)" ('WooHoo' ft. Nicki Minaj). Ignoring all this sexual gimmickry, the first half of 'Bionic' is excellent dancefloor material. Having worked with electronic and underground acts like Ladytron, Goldfrapp, Le Tigre and Santigold while recording this album, Christina has produced a sound that's sharp, funky and perfect for dancing.

To her detriment, at about the halfway point, Aguilera returns to a number of slow, soul ballads. It's a lull, as only the string and piano-laden 'I Am' really holds your attention, but with one of the most powerful and recognisable voices in pop music, it would have been a shame to waste it. On the whole, 'Bionic' feels too much like a marketing experiment to be really great, but it's perfect for a night on the town.