We took Caitlin to see it on Friday night, a few friends went with us.
Everyone liked it, I'd say half of us liked it better than the second one, and most of us liked it better than we expected to. It has a lot fewer pop-culture references than the 2nd one (which was bloated with them). And the medieval high school was really funny.
Overall, it was pretty entertaining. As long as you don't go see the movie with the eye of a movie critic (and why would anyone do that to a movie that's obviously geared toward being entertaining for both kids and adults), you will probably like it.
Never trust a tall dwarf... he's lying about something.