We did this last summer. It was *awesome*. I would totally do it again!
Does that answer your question? ;-)
Okay, a bit more detail. You get put into a small group of about 10-12 people. You are driven around the studio lot and you get to see a number of outdoor sets used in WB productions. There is a lot of variety, so any of the WB shows you watch will be represented somewhere. Then you stop and get taken to one of the Friends sets (it's the coffee shop, if your'e familiar with that show). You can take pictures, but you can't go in the set.
Then you go to the prop building. They have a ton of cool props, with cards next to them to show what movies/TV shows they have been used in. This is actually a working prop department, so you will also see tags for things that production people are reserving and might want to use on their sets. You are given a brief tour, then time to wander around on you own.
After this we went to the vehicle museum, which houses vehicles used in famous movies. Here they take a picture of you in front of a green screen and paste it on a background for you. For us, it was the Hogwarts train station. The picture is printed and given to you (included in the cost) at the end of your tour. One picture per group.
Next you visit an actual set of a current television show. It will be a show that is not filming that day. I did not know this was part of the tour until we were there, but now that I know, I would ask when buying our tickets (at the WB counter) if we could get on a tour that goes to a specific set. Once you're on the tour, you don't have a choice of set. You are not allowed to take pictures on the set. The guide actually locks up your cameras.
Lastly, you go to the WB museum. It was incredible, and I was sorry they didn't let you take pictures in there. It has costumes from many different WB productions. When we went in July 2012, the entire top floor was all Harry Potter props and costumes, and the kids loved it.
So yeah, totally worth it! Way better than the tour given at Universal Studios, most especially because everywhere you go, you can tell that this is a *real* set that is currently in production.