I did it last November and it was very enjoyable. I found that our guide was very friendly, had great showmanship skills, and knew the answers to a lot of my backstage questions (or maybe he made them up). You do get little earpieces to wear so you can always hear them over the din of Main Street.
We started with a long walk down Main Street, learning about the start of the Florida project and some of the names on the windows (a mini version of Connecting with Walt), we wandered through the hub and down into Adventureland and Frontierland, went backstage to see where the trash was handled and saw all of the MSEP floats and how they were driven. There was a mediocre lunch at CHH, a discussion of the Tiki Room as we watched the show (POTC was closed at this time) then a long talk about Haunted Mansion and a ride through it. We finished off with about 30 minutes of walking through the Utilidoors.
When you are backstage you could ask questions about the park and get the non-Disney answers, which was cool as I learned about the workings of talking Mickey and Turtle Talk. Definitely come prepared with a few questions to make the tour even more enjoyable.
They gave out water before the tour started but none during it, so make sure you have some available.
