I can see him being easy to kite if you have a support or tank with you, but for a lot of champions they can't keep him off. Any mage without good CC, any immobile melee, and probably most ADC's.
Okay so beyond his long term movement speed buff that will most likely let him out chase anyone in long duration chases (or even short duration), his Q is going to not only pull him a short bit to you, but also keep onto you if you do dash, AND bring him to the other side of you. So while his Q doesn't make him super mobile, he can effectively double the dash distance by going to your other side which is most likely your safer side (towers, team, your base etc.).
Than he's got his fear. His fear lasts long enough and with how bursty he is, a warwick who is ahead could possibly kill a squishy with a Q>E2> basic attack+hydra+Q before your fear breaks. This is potentially where he needs to be tuned down. He can be really bursty which afaik is out of his nature and not intended unless he is extremely ahead.
For warwick though just in case you did somehow elude him with constant movement speed, a short distance closer, and a fear to keep you from running away or fighting back, he's got his ultimate which can reach some very powerful ranges. Even if he misses, his ultimate can be the difference between him getting to your or not. But if he does hit, for squishies and many bruisers it can be the kiss of death.
Saying Warwick is hard to kite isn't fair when he is pretty much a diver like Vi. Every single one of his active abilities is a tool to get into the fight and keep onto enemies. He's got tools built into his kit that allow him to stay into the fray of a team fight (such as passive healing, Q burst healing, E damage reduction, ult healing). So I very much think he is a diver.
Again me listing out his kit isn't an argument for him being overpowered. Its an argument for him being difficult to kite and playing similarly to a diver. And for a diver, he seems to have pretty low cooldowns (except for his W which is not a mid combat ability but can provide combat buffs even when its off cooldown) and not enough down time for melees.
Potentially one of his issues is that he is very good at getting to ranged champions and sticking to them whilst being able to duel melees just as effectively, especially with his E which forces melee's to disengage or do much less damage and than be feared.
Riot also might want to take a look at his early game, seeing as he doesn't have a particularly weak spot during the game's whole duration.
Well anyones I disagree that Warwick is hard to kite. This post turned out longer than I intended but oh well.