Brutal, I only got through 16. The snow was pretty deep, and it was at that uncomfortable temperature where you break the surface and sink to the bottom, but the resistance is still very high.
Some of the routes that make sense in the non-winter months were completely terrible. 3 is a fantastic example of counter-intuitive route choices. I went left of the line to stay on runnable trails, but the open field was just a physical battle. It would have been way faster to take the trail closer, then cross the uncrossable marsh. My bad.
Other than that crap that was my exit from 9 and missing 16 but realizing it pretty quickly, my navigation was good. Physicality was high.