What should I say? Irelia is amazing. I've had a positive KD Ratio EVERY game I've played with this build. She is a tank, but this tank can match the damage of my previous favorite champion: Akali.

Pros:
Tank
Fast
Lasts longer in lane than almost anyone
Good for ganking
Able to swap to jungle anytime it's needed
Only tank carry I know

Cons:
The power goes to your head, and you run behind the enemies towers for kills. (Or maybe that's just me) Honestly the only thing I can say here, is that she starts only "good" and by end game if you haven't messed up completely you are near godly. I had a game where I went 7-9-3, I ended with 30-12-7.

The only change I would make to runes depending on the player's style:

The Quintessences could be changed in any way. More health regeneration means longer time in lane. More speed means more aggressive game play.

The only thing you can't figure out by looking up top, is that you sell the Wriggle's Lantern when you are ready to buy Guardian Angel. The 5 Health Potions and the Cloth Armor combined with Hiten Style allow you to stay in lane long enough to get the Gold you need for Wriggle's Lantern, and usually Boots of Speed as well. I even grab blue buff before I go back if nobody else needs it. (Unlimited Mana is always nice!)

I will add more detail to this build over time, but for now you have what you need! Let me know what you think, and vote it up if you like it!