Our guide was lovely and gave a great overview of the city and Venetian art. She was early, stayed a bit late to finish, and was great with our young daughter. Our only small complaint is we sometimes exhausted her knowledge of certain technical points, but I imagine this wound not be an issue for most - she was quite knowledgeable.
It was very rewarding to have a private guide to the Accademia in Venice! Our guide put everything in context for us so it was not so overwhelming. She also took us on a wonderful walking tour of the area and pointed out interesting sites such as the Dario Palace "the house that kills". Google it for info. Quite spooky!