We did both our first time at FW and even though my kids were "littler" when we went -- we ALL agree we will NOT do the BBQ again. It was the worst character meal we've ever done. (Maybe I just hadn't read on it enough...but believe me I scour these boards and guidebooks before we go....)
The BBQ is somewhat like controlled chaos -- it's a character free-for-all in the dancing area. The characters do not come to the individual tables like at most other character meals. (Likely not important to your 15 year old...but maybe to others planning their trip!)
We enjoyed the Hoop Dee Doo (although our son got a fever there and slept through most of it!) and we are taking Grandma and Grandpa this time so we will likely do it again. I think even 15 year-olds will enjoy it! (hey it's Disney -- what's not to love?! ok...the bbq but I will leave it at that!)