Viktor is still a weak champion compared to other AP champions that are meant to carry a team. He needs ratio buffs, a passive buff, and range buffs on his "Q", "E".
Don't even dare take him mid till they buff him. As a tanky CC mage he doesn't do anything special. If you miss his main CC move then your pretty much useless in a team fight. He can't support because he doesn't have the extra slot late game for wards (because of his hextex core -whatever its called-) or a solid CC combo to keep the other champs at bay. His CC doesn't do damage either, which really puts him at a loss compared to swain and alistar, or blitz.
I like the idea of viktor, but I feel like there wasn't a true effort to make him into a quality viable champion. No disrespect intended to the Riot staff, but with the existing AP carries in the game today viktor comes up horribly short. I won't ever play him in a ranked game, or a dominion game unless he gets major buffs. He's not even fun to play in a coop because he gets KSed by the stronger champs.
That's my two cents and I hope I didn't offend anyone. Happy New Years to all!