I took my Pug out on Saturday... it had warmed up to freezing and things were a touch slushy with a few icy patches and for this no bike I have is any better. I was rolling on my Endomorphs at 10 psi.

The only thing a fat bike is not good for is ice, unless you are rolling on studded tyres or find some chains.

I have a dedicated winter bike with studded tyres for those icy rides and also have an Extrabike with an electric assist that makes it all wheel drive... it does not get much better than that when it comes to stability, speed, and traction.