It is a tram tour. There are a few pre-planned stops, like to see the set of Cheers, the New York street scene, the Chicago street scene, etc Plus it's possible you might have an unplanned stop if there's something interesting going on that day. You get to see people/maybe celebrities walking around.
When it used to be called the Burbank Studios, it was a less organized, more impromptu experience, operating out of a small office. Now it is a big commercial enterprise with advanced ticketing, tours leaving every ten minutes, a new visitors center/ gift shop. Still, it is just about the best tour experience you can have about the movies/tv. Very interesting and informative and worthwhile.
If you want to have the best chance of seeing something *extra*, it's probably best to go early in the day, midweek. I think Sundays are slow and shooting outdoors has wrapped up before the end of the day.
I took the tour this last spring and I enjoyed it. My ultimate favorite part was seeing props from the Harry Potter movies in their museum. I LOVE HP!!! They also have props from other WB movies in the museum too. So then you take a tour of the lot, see a part of the prop warehouse (they have the biggest prop warehouse in the world, but since you only see a part of it, it didn't look that impressive), we got to see where they shot General Hospital before they decided to tear it down and the set of the Mentalist, and they also recreated a part of the set of Friends.
I think the tour is more exciting for ppl who actually watch tv shows made by WB bc they shoot the shows there on the lot. I'm more of an ABC show watcher, so when they said the Mentalist, I was like, "What's that?" I also never watched Friends, and the tour was really big on Friends, so I thought that stuff was cool, but I wasn't jumping for joy. But I did like it when we would drive through the lot and see the different facades they had & what was shot there. And of course, one of the best parts was visiting the gift shot & buying gelato!
Its pretty much as shelemm and Disforever have described before the start you get to see a film about the history of warner bros which I found to be a very emtional film particular when they talk about the cartoons. When I went I saw the friends set , sets from the Chuck , the batmobile , Harry Potter flying car , cars from the maxtrix and the mysrya mahcine. Also saw props from the harry potters films and the murel I think I saw as well and the WB water tower unfortunely I didn't see the Warners . Not to menen the shop with displays of the characters of Watchmen at the moment. From the shop I got Tiny toons and Freakzoid , a looney tunes t-shirt and a postcard