Fizz is a relatively new hero and is unique in many ways. He has an incredible ability to escape almost every team fight with low health, he can easily go in and burst the carries down, and he can summon sharks!

Pros:

Good passive that really saves you sometimes.
Epic assassinations late game.
Almost ungankable.
Hard to kill since he's hard to catch.
Did I say he can summon a shark?
Lots of gap closers.

Cons:

Requires a lot of skill, timing and reflexes to be effective in the long run.
Hard to farm with unless he's fed. (His Playful/Trickster can be epic when you have some ap)
Dies pretty often when he gets caught.
Squishy.

The rune setup is pretty