The BRAVO cable channel from time to time broadcasts past Cirque du Soleil performances. If you managed to catch one of those it would give you some idea what to expect.
I was not able to see them during our December trip (they were on vacation!), but the performances on BRAVO are VERY impressive, and I hope to see them next year. Though the prices are 5-10 times what you would pay for an ordinary circus, this is extraordinary, and more than just a circus. If it's any consolation, the Orlando prices are less than the prices for their shows in Las Vegas.
A 7-year old boy should be OK; tell him it's the best circus in the world (no lie), but no animals.