What I dislike is he doesn't offer anything.
His engage comes with nothing to disengage (rakan can W in, E away), so in a 2v2 he's literally having assassin syndrome with diving carries next to supports.He can't really help his ADC out with hard poke (play pyke into a cait zyra lane, no more needs said.) as his only healing is for himself and he doesn't give shields. A lot of passive "eat it up" supports have heals,shields or damage migitation to help laning phase more, be it alistar's heal or braum's E to negate the problem or even thresh's lantern.
The big question for pyke is: are his assassin qualities worth his absolute lack of utility? Currently, I don't think so because laning will go much smoother with a rakan or alistar, if pyke gets behind he won't have any utility to save the game.
The only saving grace stopping me from calling him worthless is his Q, which can pull a pretty important target, but if you're playing him for his hook and kill setup, blitz seems more consistent to learn in the long run. His ultimate is really strong tho, but I feel like his ultimates potential when really ahead is what gates power budget everywhere else.
...but we'll give him more time. tbh i'd take removing that hp -> AD passive and just nerf his ult a little so he has to either build raw AD to be a true assassin, or he can choose to have weaker ults for the sake of diving into fights with his E.