Torcello is considered dull by some because it is sparsely populated (fewer than 100 people) and kind of wild and deserted-looking. It is where the settlement of the Venetian lagoon first began; its importance declined after epidemics of malaria and pllague decimated the population of the island. At one time 20,000 people lived there, today it has fewer than 100 inhabitants. It has only a couple of cafes (one is quite fine and beautiful, with its own garden, and is run by the Cipriani hotel/restaurant family) and no shopping to speak of except for one antique store. However Torcello has a church and a cathedral, part of which dates from the 7th century, with exceptionally beautiful mosaics and for me Torcello was an unforgettable experience.
You can't get lost on Torcello, there is really only one path, Fondamenta dei Borgognoni, that leads from the boat landing, along an overgrown canal. It takes about 15 minutes to walk to the Cathedral. You will cross a stone bridge, passing the very nice Locanda Cipriani restaurant/inn mentioned above. Past that you will quickly come to first the church of Santa Fosca and then the Cathedral of Santa Maria Assunta.
In the cathedral in front of the altar is a beautifully carved marble pulpit incorporating part of the original from the 7th century. You will note the Byzantine style of the architecture and the mosaics. The most striking for me was the Weeping Madonna set on the gilded background of the half-dome. One book called this image "A sad young woman holding god". On the opposite wall is the mosaic of the Last Judgement.
The nearby church of Santa Fosca, in the form of a Greek cross, was started around the 11th century. It has a spartan interior, beautiful marble columns and a wooden roof. Nearby are two 13th century palazzi with artifacts and sculptures.
On the grass in front of the churches is an ancient stone seat know as "Attila's Throne", though most probably it had nothing to do with Attila.
Torcello can be reached by boat from the Fondamenta Nuova on the north side of Venice proper near the Church of the Gesuiti. The boat also stops at Burano. You can also get another boat, #14 from the San Zaccaria stop. The trip to Torcello takes about 45 minutes and is very relaxing.