I am a Shaco main, with 70k points, not that much but I only recently started maining him
At times I feel like his kit is unfair, but always fun. There's no better feeling in league than to play a Shaco game, be it AP Top, AP Support, Jungle, Mid, whatever, he's always fun. His low cooldown blink/invisibility/crit buff is the main reason I think his kit can at times be unfair. His boxes are balanced in a way, meaning you can get away from a stack of boxes in time before they burst you down. Even if Shaco goes ad, his boxes still do surprising damage. His E is a point and click ability that's probably the main reason people play AP shaco, with a 100% bonus AD and AP ratio, it can do up to 1000 damage with 750 ap. His ult is a major advantage, and sometimes an ability that can save a Shaco with a good reaction time. The fact that it does 50% less damage, and takes 50% more damage than Shaco is the balanced part of it..
And yes I know that Shaco is easily countered with Oracle and Pinks, but that is non-existant in my elo. And I'm wondering if he'll ever get a rework, Sion/Poppy scale?