Honestly, it's the best way to see Venice. There's literally something beautiful around every corner. The Rialto and San Marc's square are must-sees, of course. They're the major sights associated with Venice, but there's a myriad of beautiful buildings and views and bridges scattered all over the city. And the only way to find them is by accident. Not only that, but you get to experience the real, everyday Venice that most tourists never see. You'll find bakeries tucked away in alley corners and lion-headed door bells on dead-end streets. You'll see the laundry hanging over wrought iron balconies in the residential areas and hear accordian players outside restaurants. Fortunately, getting lost in Venice is the easiest thing in the world. You see, the signs that point the direction to the Rialto or San Marc's aren't exactly accurate. If you follow them, you end up in some abandoned square with no idea where you're suppoed to go next. If you don't follow them, you somehow end up at the Rialto. And once you cross the Rialto (which is actually a bridge, not the name of a river like I thought), it's only a matter of time before the alleys spit you out into the San Marc Piazza.
I was in Venice during Carnivale. It was freezing cold out so the streets weren't as packed full of people as I had been told to expect. Actually, the city didn't feel crowded at all but there were elaborate masks absolutely everywhere - on people, in stores, on stands in every street wide enough to hold a vendor. There were people in full blown masquerade costumes and even the gondalas were decked out in fine array. In the spirit of the day, I bought a mask myself. I didn't wear it very long (have you ever tried wearing a mask with glasses underneath? It's really awkward), but I now have an honest to goodness Venetian Carnivale mask :)
Before I posted this, I kept trying to think of ways to describe what it was like to spend six hours walking around the city. Only two words came to mind: cold and beautiful. I'll be going back in a few weeks to see what Venice is like on normal weekends and to go inside San Marc's and a few other places instead of just admiring the outsides. I'm desperately hoping that it will be warmer by then. I might have something to say besides "cold" and "beautiful" then ;) Until then, though, these should give you an idea of what Venice is like: