I am sure you know that by level 11 most champions have gained more than 30 armor out of their passive armor/level gains. You know... that thing that Thresh doesn't get.
As a matter of fact, his passive is pretty much just a little free AP on a champ with mediocre AP ratio's for a large chunk of the game if you aren't good at collecting souls. If it wasn't for the interaction of souls with his Q it would be an underwhelming mechanic, and TBH i would much rather he got armor/mr out of the passive than armor/ap.
That being said, curious to see how he plays out in the competetive scene because that lantern throw is unique and he seems like a nice counterpick to blitz. His abilities have some inherent weaknesses to them, notably extremely long cooldowns on pretty much everything except E, and he isn't quite as dangerous with the grabs at blitz is. He could have some nice zone control in teamfights, and he should help other tanky allies initiate or squishies disengage as well so it seems like he has nice utility. The question is, is he strong enough as a support in lane to help his ADC win the lane, and does his utility continue effectively enough through lategame.