I wear wellies mainly for gardening, and last year when we had heavy snow, as although we live in the suburbs of Leeds, there was about six inches on the pavements between our house and the bus stops. Usually I'd wear hiking boots in the snow as they are warmer, but on frozen snow the wellies had a better grip.
It's worth remembering that wellies don't keep your feet warm, so if you're intending to wear them for a long period of time, buy them big enough to accommodate a pair of thick socks.