Hey guys, I'm Eta Hope, and this is my Yasuo Guide.

Even though Yasuo just came out on live today, I have been playing him for a couple days on PBE, and have gotten the hang of him. While you're lucky to play Yasuo currently, since everyone autolocks him, it will be better in a couple days. Yasuo is best played in the mid lane, but can also be played top, and can jungle alright. Yasuo is a resourceless champion, making him extremely powerful, since his abilities are spammable, and has an amazing passive Way of the Wanderer. Yasuo is a high mobility, all in champion. He has potential to snowball out of control when placed in the right hands.

Pros

High mobility
Can snowball out of control
Counters most ADC's
High damage
Great chasing potential while minions are nearby
Two forms of CC
Double crit chance
Passive Shield
No resources
Short cooldowns

Cons

Squishy
No real escape
Gets shut down by CC
Knock-up can be hard to land at range

Marks: I take 9 Flat Armor Marks to make your early game damage as high as possible, as we will be building crit, armor pen, and attack speed.

Seals: 9 Flat Armor Seals are required on Yasuo. He is very easy to gank without his Steel Tempest at 3 charges. You need the extra armor to escape alive from any ganks.

Glyphs: I take 9 magic resist glyphs because ideally you'll be against an AP enemy, and so naturally, you'll want to mitigate some of their harass.

Quintessences: I take 1 AD to boost your early damage, and 2 life steal to give you some early sustain, even without building a vamp scepter.

Yasuo should be counter picking a squishy caster without much CC, such as Katarina. When choosing Yasuo, you want to have a couple team mates with a knock-up, so you can ult onto their knock-up. Play passively within the first 3 levels, then begin to harass the enemy. Dash though a minion with Sweeping Blade, hit them with Steel Tempest, and dash back through a DIFFERENT minion with Sweeping Blade. Either ask your jungler for an early gank, or wait until you have poked your enemy down low enough to all in. Most people will underestimate Yasuo's pre-six Last Breath damage, so use that to your advantage. Be sure to push the minions to the enemy tower, and roam constantly. The most pressure you can put on the other lanes, the better. Once team fights start, either try to charge up your Steel Tempest, or have a team mate land a knock up for you, and use your ult Last Breath to START the fight. Use your Wind Wall in front of the ADC, so that they have to re-position in order to do damage. Last Breath gives you 50% armor penetration for 15 seconds, making picking off kills on tanks extremely easy, even more so if you already have your Last Whisper finished.

Yasuo is a great farming champion. With Statikk Shiv, Yasuo can Sweeping Blade into a group of minions, and instantly Steel Tempest for an AoE clear with Statikk Shiv.

As Yasuo has a very new and original kit, there are some champions that make him much easier to use. My favorite team with Yasuo is
Top - Zac
Mid - Yasuo
Jungle - Aatrox
Support - Janna
ADC - Caitlyn

This team is revolved around everyone but Caitlyn having a knock-up, so that Yasuo has many chance's to use his ult Last Breath. With Yasuo being extremely squishy, Zac is a great champion to be played with him. Zac is extremely tanky, having tons of CC, and great engage, Zac can CC the whole enemy team, giving Yasuo easy kills.

In mid lane, Yasuo is good at countering most AP casters. However, there are a couple that do very well against him.

Fizz - With his 2 gap closers and being based on AA melee attacks, Yasuo cannot escape from him, and Wind Wall can only be used to block Fizz's ult Chum the Waters.

Akali - With the ability to stick to people with Shadow Dance, with no way to escape Yasuo is forced to duel Akali, which is never a good idea.

Teemo - Everyone knows why. With a blind Blinding Dart, this little Yordle counters most AD champions.

Riven - While Riven mid isn't common, she can beat Yasuo before level 6, and it is easy to feed a couple kills early to her by accident.

http://www.lolnexus.com/

I have just started using this site a couple weeks ago myself. It it EXTREMELY helpful, as you can see everyone's rank, know who is pre-made with who, and knowing what to expect of the other team. I highly suggest you all try using it out, all you have to do is finish champion selection, wait for the loading screen, then go to LolNexus, and type in your summoner name.