There is nothing satisfying about him. There is nothing clever about him. There is no late-game fantasy.
He just has gimmicks. His E permaslow is a gimmick. His Stealth Blink is a gimmick. His Traps are a gimmick.
The thing about gimmicks, though, is that they work once, or not at all, or maybe a few times. Then they fall off.
It's not healthy design. It's not clever design.
Riot, pick ONE gimmick that you feel represents his playstyle. Modernize it. Then fill out the rest of his abilities with something reminiscent of current Shaco.