Because I instantly loved it, Dubstep has always been one of my fave genres but Britney will finally bring it into mainstream. I think a lot of people dont like it because it's quite different yet at the same time its so similar to music thats out at the moment.
Its brilliant. Delivery, vocals, that BREAKDOWN/BRIDGE. Her swag in the "gimme something good" lines is just The beat builds, and it grows more & more into a monster as the song progresses.