forgot to mention last whisper sorry about that. Last whisper should be taken more early game as it gives armor pen and damage increase. personally i would change it into black cleaver as its bonuses are even better but the price is also higher so keep it as alternative if you got enough gold.

P.S about previous comment i like to say that your damage stays low until you buy attack damage items which is only after spending 3500 gold or more for the other items. Change the order to make it more usefull.

err...

Last Whisper?

0 armor penetration will make you fail epicly vs tanks even with the bloodrazor. Only 55% crit chance makes you weaker then the full crit yi build while your attack damage is almost the same. Cooldown reduction runes are meant for AP yi not dps yi. Health runes aren't necessary as you got both health pots at start and later on spell vamp. Starting with wuju style lowers your farming drastically at start of the game and makes you an easy target for ranged champs as you can't get to them fast enough. Starting with attack speed only until mid game is very bad as you'll get killed by those who increased their damage .

Bad build -1