Even the lightest amount of snow makes things VFR difficult. The transitiion from rain to snow can be pretty quick. As stated above, it builds up in some interesting places. On my Auster the wing roots, struts and over 50% of the windscreen. And that occurred in little longer than it took for me to notice the rain wasn't anymore!
Flying after a light dusting of snow can be pretty excellent. Cool, stable air, bright light and on our strip the capability to fly a couple of circuits and check the consistency of touchdown points.
Flying after a heavy dump - impossible for us. Couldn't get out of the hangar without loads of digging and the rolling resistance meant taxiing needed loads of power. And then when it thawed even more rolling resistance!