Is Genji Overpowered?

I've been playing Overwatch since before release, back in the early beta days even and I've seen the game go through a lot of different changes both big and small. But every time I come up against a Genji main, I'm triggered beyond belief. He's so overpowered in my opinion, his ult is unstoppable, he can deflect everything etc. Then you get other characters like, Mcree - his ult is stopped by a simple flash bang.. even though genjis would carry on.

Do you think he needs nerfing?