The car can be used in the snow and is *acceptable* with real snow tires. Blizzaks or Nokians are generally about the highest rated.
That said, even with snow tires it's only OK. I.e. if you're driving on flat roads with less than 6" of snow you'll probably be ok. But get a very sizable hill and there's a good chance you'll have some trouble with it. I live on a hill in upstate NY where I normally go up the hill to work. But I've gotten in the habit now to where I go around the other direction, down the hill via an alternate route if there's much stuck on the road. It will generally make it up, but if it's slippery stuff, I'm forced to engage the gas engine, and spin the tires and get the traction control working hard to the point that a normal 20 second trip up the hill takes a couple minutes and the traction control error light comes on.
That said, I'd disagree with Raja's comments on difficulty stopping. It's a 2 ton car,but so are plenty of other vehicles. AWD doesn't help you at all in that scenario so between two different 2 ton cars, it will come down to who has the better tires as far as who will stop quicker.
The other issue the C-Max has is that it has automatic radiator shutters, so if you go through stuff with more than 6" of snow where it gets up to the bumper level and then jams up in there and freezes, that can damage some expensive parts. I've not had that problem for the couple years I've owned mine, but I did hear it one time last year where it got snow in there, froze up and then I could hear the shutters repeatedly clicking trying to open or shut and not able to. Thankfully mine didn't seem to be damaged and cleared themselves out after some time. But I've heard reports of others doing worse.
So I'd say around my house I'd take it to the ski slopes because around here there's no more hills to climb than I have to deal with going to work anyway. But if you're dealing with real mountains it will be a bit more iffy.