I've seen my little brother watching it, although I'm not sure if he legitimately enjoys it or if he's just watching it to pass the time for something else. He loves Adventure Time and Regular Show, though.
From what I've seen of the show, it looks like garbage. I know I'm not the audience, but I can still tell the difference between a good kids show and a bad one. Sure, I've seen crap as a kid, but nothing I've had fond memories of or even remember, and this seems like one of those shows I doubt most kids will acknowledge or remember years from now.
But the show itself just irritates me. The premise is that the boy's sisters use him as a lab rat, but he just steals their stuff and uses it for his own wants. Not to mention Johnny is just an unlikable, stupid little prick, even for a kid. The rest of the cast isn't any better, either. That, and I hate the animation. It's a prime example as to why I can't stand flash animation in TV series. It just looks ugly to me. Also, a lot of the voices sound vaguely similar.