The film feels much less a kid's movie than the first two films. Like before, there are all sorts of visual quotes and references that knowledgable adults could enjoy. At one point, for example, as Prince Charming is preparing a stage production, a group of dancers in the background are doing a Chorus Line routine while Charming wears pink dancer's warmers. At another point, Shrek, who has gone to find Arthur (as in Camelot/King etc.), finds him jousting with --and losing to-- Lancelot. Artie has a thing for Gwen. When they come across Merlin, he's projects himself like the Wizard of Oz and wears a hospital gown length robe. I'm sure that since many high school kids have only vague ideas of who Lancelot and Guenivere are, the humor is lost on many kids.
One of the things I enjoyed seeing as a graphic artist were the textures--the beautifully modeled skins of the people and Shrek, Shrek's knitted shirt and homespun clothing, the hair of Charming and Artie-- and the detailed matte paintings.
I had fun with the film and laughed a lot.