Haven't had any problems getting around with my Jazz, neither has my wife in hers (she came home laughing the other day as she had driven past quite a few cars that were either stuck or being pushed up hills). Tyres are 'Michelin energy savers' - so are not particularly designed for snow.
The Jazz has the advantage of front wheel drive (where the weight of the engine is over the driving wheels), it also has the fuel tank mounted towards the front of the car which also helps keep weight over the driving wheels (keep you tank topped up to help with traction and also in case you do get stuck for a long time).
Rear wheel drive cars haven't got a lot of weight on the driving wheels (the original Volkswagen Beetle had the engine in the rear, which together with narrow tyres made it pretty good in snow), and also the front wheels tend to build up a wedge of snow which the car has to push along or drive over, which adds to the problem.
Rear wheel drive and wide tyres are the worst things to have on snow - BMW owners like my neigbour can't even move on flat ground, let alone tackle a hill.
