In winter, Venice shows what is probably its genuine face.  With most of the noisy crowd of tourist reduced to just a handful of art lovers, the beauties of the Serenissima are more readily appreciated. No noise, no waiting, lower prices, slower paces. 
Moreover, you can even meet true Venetians in winter, a people you would consider as extinct in every other period of the year. Which is a blessing, if your aim as a visitor is to try to live the town from its very inside rather than to merely scratch its ready-made-for-tourist gleaming surface.

For photographers, there are a few more advantages.
In winter days the sun seems never to rise, rather it remains low above the horizon line and somewhat its light is scattered in the sky, as if it was shining through a window of polished glass or alabaster, and the shadows are as long as church aisles.
Sunrises last for ages, and so do sunsets. It is breathtaking just staring at this glorious representation, watching the sun while it slowly emerges from or dives into the pale green waters of the lagoon, occasionally peeping through layers of bold rainy clouds at the horizon and casting its faint rays on the facades of palaces and churches.