First listen... meh. Didn't do anything for me.
Second listen... actually really liking it. Heard it on Moyles this morning and haven't been able to get "I've only got 4 minutes to save the world" out of my head, but this is also the critical problem. Most of the song that is stuck in my head isn't being sung by Madonna!
Also, it isn't really her. Very Nelly Furtado, I thought. Obviously thats the influence of Timbaland, but I don't think this is for Madonna.