I biked every day of the year for about ten years in NYC with an average commute of about six miles each way. This included a ride over either Manhattan or Williamsburg bridge, which get icy faster and stay slushy longer than terrestrial roads.

Always on regular 23c or 25c road tires.

I usually fell over about once per winter, which always kind of sucked. But by my estimation, riding the subway was a more miserable kind of experience.

You slide around a bit but you get used to it. The bike is usually but not always more stable than it feels.