I ran them year-round on my Maxima for a while. My dad also ran them year-round on his car.
The only complaint is that the heavily-siped silica tread is loud and sounds different on every surface.
Traction is impressive in just about every type of weather, and I have driven through 12+ inches of snow, solid sheets of ice, and everything up to record heat with them. You're still limited by physics of course, so yes, you can spin your tires on ice. So they're not a substitute for driving skill, but they sure outperform everything but studded tires in the winter, just about everything in wet weather, and still hold their own at all other times.