The Zed in the snow is quite good fun. I quite enjoy my trips out in the snow. If you had to choose a car for the snow, a Zed would not be it - my wife's A class Merc is much much better. But for the shear sport of trying to make progress aginst the odds, you have to love the Zed.
Gentle inclines can be a bit of a problem, it depends on the nature of the snow/ice surface. There are times when nothing works - lost momentum, and had to give up - but this is rare.
As someone said, the back wheels want to move from higher to lower ground - including the camber on most roads. I have regularly found myself moving along the road at a bit of an angle, with the back wheels near the curb and the front wheels near the centre of the road. But once you get used to the strange position, its actually fine. When I get to a more grippy surface, I can get it straight again.
I carry a spade and a bag of grit in the car - not only for digging myself out, which I have had to do several times, but it also adds a bit of weight over the back wheels.