My 9-y.o. LOVES Kick Buttowski! And although the other parents on this site may think you otherwise, I personally think this is actually an okay show! The humor can be a little crude, but many episodes dredge up a chuckle from adults as well (at least in our house). The animation is great, much better than the garish Phineas and Ferb. And because many parents have made the comparison, I would like to say before anything that it is similar to P&F by levels of violence, rudeness between siblings, moral values, and blows it out of the water in humor and visual quality.
And sure, Brad and Kick Buttowski are rude, and the friend dislikes the brother as well, but that is because Brad is... let's face it... a flat-out jerk! I do not at all get how Kick is rude to his friend, however; in fact, their relationship seems great. The only respect-type thing I find a bit questionable is the fact that Kick and Brad occasionally lie to and trick their parents... not little lies, but big lies, like scratching up Dad's prize vintage car, disobeying serious rules, etc.
There is no use of mild curses that I would find inappropriate for small kids, such as "crap", like in many other, worse, Disney shows. The use of the word "butt", however, seems to offend several parents, according to the other reviews, and although I personally have no problem as long as the word is not an insult in our house (eg, "You little butt of a brother!"), I would like to put that out there.
As for violence, there is nothing but mild cartoonish stuff here. Kick does some crazy stunts and isn't the most safety-wise, but it is all in good fun and WILL NOT have your children literally jumping off the walls, destroying the house, leaping off stairs, and skateboarding off cliffs. And when Kick does stupid thrill-seeking acts, he often pays the price in injury, unlike in other cartoons, where characters get bopped on the head with a hammer or shot with a rifle, stay dazed for one second, and get back up.
Underneath the word "butt", the action stunts, and the rude brother that so many parents here point out, there is a comedic, child-appropriate, fun show that actually has some good messages. Yes... good messages. Sure, there's the brother feud, but deep down, they love each other, and that is portrayed on the show. Viewers are reminded the importance of friendship often. Kick gives a treasured old trike he wants to hang on to to a sister who needs and will play with it more. My children have never had any sort of negative change in behavior from this show, and I have found they don't really absorb the bad as much as we are led to believe, at least at age 7-9. No, there wasn't a huge positive change, but the show is great fun. If your children are different and absorb the bad, a simple reminder of expectations for respect and safety will be good.
All in all, this is a good show (for kids 5+). Kids 7-9 will appreciate it most and be least affected by the little bits of "bad" present in every show. My husband and I find it well-made and good for a silly chuckle while my son and occasionally his brother watch. If you have a fun-loving 7-9 year old boy, this is a show for you.