my fiance & i did this tour in november 2003 & are doing it again with my parents during our wedding week at wdw this march. it was a great experience, started with the tour of living seas, then the backstage area of living seas, the caregiviers & the dolphins, it was very educational & fun to see & interact with the dolphins. i loved hugging them & the picture we got.
as for the 13 & up requirement, my guess would be they want a more mature teen because of liability issues & they dont want kids pulling or becoming over excited with the dolphins. plus with the instructions in the aquarium, kids dont always listen.