Pros
+ One of the best junglers ingame thx to huge lifesteal
+ Super ganker. Apears from nowhere with a highly damaging long stun.
+ Best chaser ingame becouse of the BS skill
+ based damage Bloodrazor + Hungering Strike will get even tanks down very fast

Cons
- Golem buff dependant early/mid game.
- Blind/Stun
- Easy to countergank in jungle
- Leaves 1 champion for 2v1 lane

When you have done the build in top, the next items will depend on the enemy team. If the enemy team got an ap is feedet you will go for Force of Natur, and mabye Guardian Angel if you get focuset in Team fights. If an ad is feedet you would go for Thornmail, or more dps for more life steal to hold your hp up when defeting him, that could be Atma's Impaler with Phantom Dancer.

You start with blue buff they get others to protect you and the middle to pull. What is important is that you are spamming your q as soon as it is ready. After that you will continue to jungle until you reach the golem and killed them, you should be at level 4 when it is, you begin to look for gangs. If there is no gangs to spot go jungle in enemy team jungle. After this you should be able to jungle by your self, just remember always got a look on the minimap (: