I saw this with my Amybear, my brother, and a friend after church on Sunday. It was proof that you don't need extravagent special effects to make a good movie. Much like Galazy Quest, the budget for Sky High was modest but allowed for a good quality and quantity of effects. It was no where near as pretty as, say, the Fantastic Four, but it was more than pretty enough to suspend disbelief.
My co-worker thought it might be an X-men ripoff, but it wasn't. X-men is about recasting racial tensions in a superhero light. Sky High is more of a teen movie, a coming of age high school story but with superpowers. The young kid with nothing to recommend him because the school hero. Literally. Some parts are a bit predictable, but others work well. The movie is generally clever and well-cast, both in the young leads (who I had never seen before) and the experienced adult in the supporting cast.
Despite the fact that this movie is not, to my knowledge, based on a comic book, it roots itself in the comic book genre very well. The movie starts with panels telling backstory and ends with some other panel fillers in the credits. The costumes and sets are bold primary colors with a bright feel that harkens back to stories from the golden and silver age. If you only like comics that involve lots of brooding and shadow, this probably isn't the movie for you.
It was well worth watching, but if you want to hold off until DVD I'd understand.