The gondola ride is a great schtick to get tourists to come into the Venetian. It works! We walked past it while strolling down the strip and I made it a point to take a ride on the gondola before leaving Las Vegas.
There is an indoor gondola and an outdoor gondola. We opted for the indoor one because we figured it would have more people-watching opportunities and we preferred to stay inside from the heat. I called to make our reservation, and while it was relatively painless, it did take about 15 minutes via phone since the person I was speaking with did not have a working computer to book the reservation... Eventually I was transferred to someone who could actually help us. We picked up our tickets at the concierge and made our way over. Keep in mind that you must arrive 10 minutes prior to your ticketed time to get in line.
Since we were only a party of two, we were given the option to "share" a gondola or "purchase all 4 tickets to have a gondola to ourselves for a more romantic experience." ($19.95/pp for indoors) We opted to share. And by golly, we were lucky enough to actually have no one share our ticketed time!
There is a camera person who takes a few photos of you in the gondola which you have the option to purchase after the ride. On the ride, you can take as many photos as you want. Our singer/gondola boat rower (what are these guys called??) was Gaetano and he was cool. He made some small talk with us and sang a few songs after we reached the one end of the canal. It was a nice, relaxing ride... but it lasted maybe all of 6 or 7 minutes. It was shorter than we expected, but we got some fun photos and were serenaded on a boat in the Venetian under the painted sky. Why not?