This is my first winter of commuting. I just kept on riding since this winter has been unseasonably warm for Ottawa. I've only gotten caught in 3 storms (5-10cm of snow) so far and only a couple days where the temperatures were close to -20C. So far the temperatures have varied between -10C and 0C.

I wear cycling boots with a couple pairs of warm socks. I just keep the tension looser on my SPD pedals than in the summer so can easily unclip. (I've had to unclip in a hurry a couple times.) Being able to upstroke when trying to get through some thick slush or half a foot of snow has been helpful on a few occasions. I do have a pair of flat steel pedals but I haven't felt the need to install them on my bike yet.