Yeah he's not bad, but he isn't quite there yet. He's very solid the first half of the game, but he has some issues to work on after that stage.
He's too easy to kite, which is a terrible fate for a melee champion that relies on AA. I know this both from playing him extensively and going up against him.
The scaling, the way it is, means he doesn't really get any stronger damage after he maxes Thunder Claws (R). And that thing is only up for 12 seconds, and has a 80 second cooldown... that's a lot of downtime.
His tank ability is a bit lacking. His CC is too weak to contribute in a meaningful way in team fights, and he only has his passive for extra protection (which is ruined by Ignite btw). That means he relies quite a bit on items that he can't always afford to survive. Combined when tanking... not very cool. Especially if you're designated initiator.
I think something along these lines would fix him right up though:
Up to double movement speed on his Q, but have it rapidly decrease to 0. Roughly the same distance covered, but he'll catch closer targets much faster, keeping his W stacks from falling off. Possibly give it a weak and short slow to let him keep up after impact, because...~
Have his E lose the slow, but for 0.5 seconds, have the fear work on champions. And have it break slows too. This means he has a fighting chance against kiting, and a great addition to team fights. Would need to have a higher CD though. And just remove the damage if even that is too strong, because he desperately needs this to even do damage in the first place (against champions).
Just a minor boost to armor/MR tacked onto his passive would help him survive better.
I'd love a much shorter CD on Thunder Claws. Let's face it, besides him being an armored bear, this is the reason we play him! It needs better AP scaling (if it should be kept), and a minor AD scaling as well. Building AD on Voli now feels like a waste of gold.
Possibly cuttting the base damage quite a bit on the skill in return. I don't care. My body needs chain lightning. Riot pls.