I've read reports that there's a problem with the brakes on the 2010 Prius.
I purchased my new Prius in August, 2009. I drove it out to Wyoming and back (highway speeds) and I drive it in city traffic (stop and go). I've put nearly 10,000 miles on it.
I don't have snow tires, so I've been reluctant to drive it in the snow. But when I do, I haven't had any problems. In fact, I haven't had any problems in snow, ice, rain or traffic. And I get 50-60 mpg regularly.
I keep my eye on the dashboard graphs - and I drive in the ECO range - conservatively.
My only complaint is the low undercarriage clearance (I've hit more than my share of potholes on the roads out here in rural Wisconsin).
I do, however, plan to watch out for the brakes, until I hear otherwise...