Both cameras are great on their own, but point for point, the Nikon wins this one overall for sure.
Competition is a great thing. Neither Canon or Nikon would be as good at this point without it. The 5D2 forced Nikon to increase sensor resolution and add video to full frame cameras, and the D600 will force Canon to put more into its next 6D style camera and hopefully improve their sensor tech. And the 6D will likely force Nikon to integrate WiFi and GPS, and improve their AF low light performance.
I'm getting a 6D and I think it'll work just find for my needs (I have too much Canon gear to make it worth switching over the differences), but kudos to Nikon for raising the bar.