I just started riding this past spring -- so I haven't experienced a winter as a cyclist...
But, I did recently buy a hybrid with fenders and a rear rack & trunk to hold rain gear and excess layers -- and with some old ski clothing I have around -- I should be somewhat prepared for a little wet and a little cold...
But, the guy who sold me the hybrid (and a headlight) is an avid cyclist and he was singing the praises of riding the trails at night with a couple inches of snow on them... He made it sound REALLY beautiful -- almost spiritual... But, I might have to ease into that one...