You're met by a local guide who's friendly, personable, and knowledgeable about the city and its history, then handed off to the tour guide at the glass factory itself. As he said, it's better to let an expert handle that part of things. The glass demonstration was shocking simply because of the ease in the master glassblower's work. He made it look boringly easy, even though it's not. After the glass factory tour, you're met by your guide and get a tour of Murano, along with some of the churches in the city and the history of them.
Overall, it was a great tour, and truly is private. You're not fighting to keep up with a crowd or struggling to hear what's being said. If you have any interest in seeing the glass blowing demonstration or touring Murano, this is the way to do it.