He's not really an issue. Most bruisers (i.e. Renekton, Irelia, Mundo, Cho'gath, Trundle, Wukong, Volibear) and some mages (i.e. Annie, Malzahar, Swain) can outright invalidate him.
In addition, he's quite squishy until late-game. If you hit him with a single hard-CC, he's quite easy to kill within its duration.
Most armor items have an additional component which counters him on multiple fronts too.
- Ninja Tabi reduces the damage from his basic attacks (and maybe his Q) by 10% without accounting for the armor.
- Frozen Heart reduces his attack speed, which also raises his Q CD.
- Randuin's Omen reduces his attack speed (same benefits as above) and reduces the damage taken from critical strikes by 10% (all of his damage is crits).
- Thornmail returns damage which he basic attacks you or hits you with Q.
- Zhonya's Hourglass can be used to avoid his knockup, potentially denying him his ultimate.
If Yasuo is running around killing getting solo triple-kills on your team, then you team has made many grievous mistakes leading up to that point.
I would suggest playing him for a few games (5-10 probably) so you can get a feel for what his weaknesses are and how to take advantage of them.
While I will admit that Yasuo can be unfun to play against at times, that does not mean that he is overpowered.