Junkrat isn't a very difficult hero, but he can easily overpower other heroes:
He can one-shot 200hp and 250hp targets with grenade+mine
His grenades deal massive dmg, wrecking shields
Mines give great mobility and quick kills
If 800hp Hammond gets trapped he is pretty much dead
He is hard to kill, because of high range and mobility
His ultimate is just a tracer bomb with better range, dmg and easier to use
He is strong especially on lower ranks, where 40 lvl guy can pop of
What do you think about Junkrat?