I agree with the last poster, Blue Man Group is very difficult to describe. I personally do not think that this show is appreciated by anyone under the age of 7 or 8. Most of it involves body language and facial expressions which little kids just won't "get" and would probably get bored rather quickly. Universal does not recommend this show for anyone under the age of 5. And all children require a ticket no matter their age, no lap sitting like at Cirque.
All that being said, I would highly recommend the show for anyone over the age of 8! It is hilarious and the fun part is that you have no idea why it's funny but you're laughing your butt off! It is very visually entertaining. Good news is that the theatre at Universal only seats 1000 so there is not a bad seat in the house! So if you're contemplating, go ahead and get the cheaper seats in the back, they are still going to be GREAT seats! Maybe even better because you get a better perspective of the stage.