A very objective and honest review from someone from Pulse Music Boards:
Ok, so I've F-ing finally heard the song. I think it sounds amazing.
I love the sound they gave it, specially when she says "tonight". The tone on that part of the chorus is very euro pop (think Cascada) which is catchy. The chorus itself is very melodic which adds to it's catchy-ness (I make up words as I go

). The verses are more mellow and less catchy. This, to me, is a great way of making the chorus pop and adds to the nature of the song. The songs stop and start and mix of music styles makes the song very interesting even after multiple listens. Think of how a club mix would work.
The bridge and dubstep is an awesome edition. For one thing, it's very "new" and it's somewhat experimental. But the best part about this is that Britney's voice is all natural and gives Britney a great opportunity to sing that part live. Not only that, but it's long enough to mix with an awesome breakdown dance. That would create a wonderful live performance and video for this song.
Finally, the song just ending without a slow fade will help repeat plays and will add to the catchy-ness (remember that word I made up above).
Honest rating? 4.5/5