I mained him for a while in top lane and jungle. He's okay. No matter what composition your team has, his only real ability is to split push.
Yes he can teamfight, with the AoE KnockUp/Slow and that Ult hitting everyone, but he's very squishy. If you buy AS to make use of his W, then you get little damage in place of sustain. If you build tanky with SotRK, he seems to not do much damage. When he's not squishy, he does little damage.
I still find him fun to use, but he has almost no favorable matchups. He loses to most everyone. He's like Jax....but Jax outduels him.