How is Viktor right now?

He seems fine to me. He has decent synergy with the runes. I'm sure there's an optimal choice for super high level play, but electrocute, comet, and aery all feel viable to me, depending on your preferences and play style.

He's still not that strong early game, but scales well. It feels like full-build AP has gone up, which is good for Viktor, since he has excellent ratios.

Tanks are pretty popular right now. He does better against tanks than a lot of other control mages.

He has decent matchups against popular mid laners. He doesn't have much kill pressure on Lux or Morg, but after first back he can just AFK farm.

He's booty. Against anyone that can waveclear well you're forced to rush E upgrade ASAP (still 1250g after the nerf) and is doubly screwed if he falls behind. His low playrate + winrate should tell you that there's no reason to pick him over better mids.

Hot garbage. Games end too quickly to get going and you are forced into getting a 1250 gold just to be ok at pushing. If you manage to get to that then you have to deal with the snowbally games and not doing damage till mid game cause the mid laner bought a hexdrinker.