Farm as much as you can. This Shen Build is very gold reliant, so if you want to can even start cull, however you will be slightly underpowered until your first back. You should have at least 100 CS by 20:00 minutes.

PRO

After your first 2 items (+ boots) You are a huge threat.
Your E-Q-W combo is great when initiating in a team fight, however make sure that you target the backline.
You have now become an Assassin, and are no longer a stupid brainless tank.
With this build you have MASSIVE on-hit-effects between your Q and BORK.

CON

VERY Squishy until full build.
Will often get flamed by teammates, especially early game (or until you prove to them that this build is in fact better than the mainstream shen builds).
Hard to play against a ranged Champion.
Very few cons to this build

Don't play in ranked until VERRRY comfortable with this playstyle.

Who the heck need team work when you are an assassin?!?!
By late game, if you have not fed at all, you should be able to 1v1 ANY enemy champion.
With your %max health damage and your on hit effects you should be able to shred tanks, however if you need more armor pen, you can swap out Hextech Gunblade with a Mortal Reminder or a Lord Dominik's Regards if they have more armor based tanks.