Some of you might be wondering, who are you and why would we care about what you think about Yasuo? The truth is, everything about Yasuo effects everyone in the League community who plays with Yasuo.
One: His Early Game
People say build stattik shiv first. Just like Tryndamere! The problem here is, with Shiv, Yasuo lacks the damage early game to assassinate. He pretty much depends on the opponent making a bad move. I don't know why this works on Trynd (It just does), but it seems to be a kind of bad choice with Yauso. I'd go for Vampiric Scepter first, and then split-build Ravenous and Stattik shiv. Note: This takes up all of your inventory space...
Two: Falling Behind
If Yasuo falls behind early, he sucks late and midgame. He can't do anything, except wait on the sidelines for someone to get REALLY low health before using his Q: Stabby Sword and get a free kill. Because if he's behind, and he leaps into a fight, he'll die instantly. Sure, his shield might migitate some damage, but all it's doing is prolonging his inevitable death.
Three: Overpowered if fed
Most people say, don't feed (Insert champion name here) or we lose! This is ESPECIALLY true. IF a Yasuo gets to full build, he can AND WILL jump into your entire team 1v5, kill half the people, and waltz away on half or three-quarters health because his crits allow him to heal massively if he has lifesteal. It really isn't fair. And to top it off, he can block everything, pretty much. With his W, Wind wall. Also, his high mobility with E, Dashy, makes life hard for everyone trying to land a skillshot on him. Aaaaand if he just so happens to find you trying to push a lane, you'll die before you can react. It'll be like "Farming happily, pushing lane, no enemies, i'm safe!" When suddenly, A WILD YASUO JUMPS OUT OF NOWHERE, KNOCK'S YOU UP AND SLAMS YOU BACK INTO THE GROUND WHERE YOU COLLAPSE AND DIE.
Enough of that.
Note: This is my first blog post, might be a bit sloppy...