He is strong but super-squishy and very vulnerable to harass prior to level 6. You basically have to make his life hell from the first wave of the game. If you can get him out of lane and force him to roam, that is a good start. From there, your supports have to be super diligent about providing sentry wards to the other 2 lanes as well. Most will fail.
If you don't do those things, allow him to get level 7 or 8 and an item or two early on in the game, it is pretty much over. He will snowball to 15+ kills and totally counter the other teams supports and team-fight.