I watched JN a few times when I was younger, but couldn't really get into it alot. Every episode was the same. Jimmy would make some invention, use it to do something he thought was good, but the invention somehow always made something bad happen/something that wasn't supposed to happen,, and in the last 5 minutes of the show, Jimmy would use his brain power and somehow always come up with a sollution to the problem that they were facing (and that he created in the first place).
Sheen was one of the more colorful characters on the show, but I would think for the spin-off to work, you would have to add Carl in there with him. Alone, he isn't very funny. But with Carl, they may actually have a show. Still, with 26 episodes ordered already, at least there will be a first season to watch to see if anything comes of it.
Whatever happened to the good cartoons on Nickelodeon? AAHH! Real Monsters, Rocko's Modern Life, Doug, the original Rugrats, Angry Beavers, and All That? I miss shows like that.