Pros:

• Great mobility
• Amazing jungler
• High damage, especially on tanks
• W ability is great for escaping

Cons:

• Easily killed when slowed after W ability is used
• Can't slow people on regular basis before you get frozen mallet
• Loses from AD carries before you get wit's end

Optional boots:
Boots of mobility (to roam real fast)
Mercury's threads (if you get a lot of stuns)

Finishing build:
Sell wit's end and buy eighter a trinity force or another phantom dancer to do even more damage.

I mostly recommend flash and heal for escaping purposes, in combination with W this will guarantee your escape from ganks (use W after flash though). You can also get smite for early game jungling or ignite to kill fleeing opponents just a bit easier.

To farm really quickly use the following skill sequence:
E -> Attack -> Spam Q (-> repeat for strong jungle monsters)