AP Shaco is one of the most fun things you can play in League of Legends. Here you have 2 abilities with 100% AP Scaling, a trap that fear's a champion while dishing out loads of AP damage, and a ability that causes you to travel the same distance as flash, while being invisible. Tell me that doesn't sound fun!

Pros

+Fun to play + Boxes have fear and high damage + Great escape + High AP ratios

Shaco has a high damage output with his Two-Shiv Poison, Jack In The Box, and Hallucinate. All of his abilities, besides Deceive have 100% AP scaling, which makes him scary mid-late game.

Cons

- Squishy - Mid-Late game - Needs items to do well - CC kills him

While AP Shaco top is a very powerful way to play him it can also fall off when you play against top lane bullies such as Riven, Irelia and others. CC will kill you. If you get stunned, you can be easily bursted down.

Viable.

free damage over a period of time. Secure kills, and watch your opponents burn!
Tired of people running away from you? Easy, just Exhaust and watch as you gain another 2 stacks on mejais!
Some say that Shaco doesnt need Flash because Deceive replaces it. With Flash you can Deceive over a wall, then Flash over another for an almost guaranteed escape
instead of flashing away from one spell, you can use ghost to stay ahead the entire time.

No Go

Waste of a slot, when it could be better used for something else
No need in wasting a slot for teleport if you cant split push well.

You can throw a point into Jack In The Box or Deceive every now and then, depending on the situation. This is the standard path for AP Shaco top.
I max Jack In The Box 2nd, because it adds a ton of damage.
Always max Two-Shiv Poison first, as its your main source of power.

AD marks for help with cs, and basic attacks.
Armor seals are really handy, it keeps you strong early game. A little bit of armor never hurt anyone.
AP Glyphs to add onto the damage you can and will do.
AP Quints for extra damage.

In conclusion, AP Shacotop is a fun little build to try, but you may run into some troubles as you would trying out anything for the first time. There is a high chance that it will be a 9v1 uphill battle until you can prove you know what you're doing. It's always worth trying something new, so if you're a fan of Shaco you may enjoy playing him AP top.