I know people think he's good but I think he's possibly top tier material. He's the only character I know of for instance, that can start and end an AP burst combo in the air (as long as they are kind of close to the ground). Considering this is such a heavily air based game this is highly significant.
Not only this but he can combo this into his super so we're looking at potentially 90AP plus hit confirm-super and all of this on a caught aerial opponent. I can't stress this enough.
You are safe from most setups in the game by being in the air, GC just might be only character where's it's actually safer to stay on the ground against him.
As more people realize this about Good Cole, I predict him being a very popular high level singles character espcially as a counter to heavy air campers.