I'm happy with my Coopers, but, like everyone is saying, they are terrible in slush and ice. There's just no grip because even though the tread looks aggressive, it's a hard compound that doesn't stick to the surface. If you like driving sideways they're fine. Getting traction is no problem, it's just that they like to spin even once you're moving.
If you're in deep snow, they will just paddle right through it with no problem. On the highway they're great. I can sit on the freeway at 120-125kmh all day long comfortably. They don't seem like an M+S tire when you're on the road, they are very compliant.
I haven't tested them out in mud yet as well, it's January...where am I going to find mud in Ontario? lol