My first impression of the song is definitely a positive one. The Dr. Luke/Max Martin-produced beat has a dance/industrial feel with a lighter, almost trance-like chorus backing. Britney's vocals have never been the strongest aspect of her music, but they lift up the song, particularly in the chorus, rather than hold it back. The over-autotuned bridge was something of a staple of the "Circus" album, and I could have done without it here, but it's nothing big enough to hurt the song.
Lyrically, the song is suggestive, but nowhere near the overt sexuality of Britney's last single, "3". It's somewhere between the cheeky vulgarity of "If U Seek Amy" and the direct-but-safer "Toxic".
The finished product ends up sounding like something that's distinctly Britney, though a continued evolution of her overall sound. There's a natural progression to the tone of the songs from "Blackout" to "Circus" to this single, and the dance club sound is getting better with each effort. While I may have a built-in bias, I like it better than most of Katy Perry's most recent album, much of which was produced by the same team. I had been worried when Luke and Martin had suggested that Britney's next album would be more electronic and grittier, but if this is a sample of the end result, I'm very excited.