I'm only at 5 months/7400 miles on my car, but I thought I'd put in my two cents.
They've been pretty good in the dry, excellent in the wet. I was driving at highway speed through 1-2 inches of water for a couple of miles during the recent Frankenstorm without any issues.
I've only had them really slip on me on one occasion. It was on a wet road, and I did it on purpose.
Haven't had a chance to try them in the snow yet.