Never as great as the first time
My first experience at KidStar was when I was 8 years old. I am almost 15 now and I still love returning to the little amusement park in the middle of the "town". But by the 4th visit or so it became dull. My friend and I had enough money to buy two wristbands (about $15 at the time) that allowed us to ride any of the rides for the day. There are only about 12 rides or so, several of which are only for small children. Because of this, $30 wasn't exactly well spent by two 14 year olds. I'd say the age range for the actual park itself is 2-10 years old, but that really depends on how easily a person is amused by the same rides.
Overall, I give the park about a 3.5/5 because of the fun that you can have... the first couple of times. A great way to spend a Saturday, though :)
-Jeseon