I think he's a great champ that's under-tuned due to the consistency of his impact.
If a team is mostly AD and you have a high AD scaling physical damage scaling carry down bot, or even vayne, you can wreck entire teams even now.
His Q is basically only for healing himself now. Its going to seem weak if you're using it on others.
His W is huge, especially when you use it on someone.
His E, in conjunction with his passive, Q, and W, is huge because it makes it so many people, including ranged, can't trade well with you even though you're a support. It also allows picks for your team, since you can be further up due to near immunity to many forms of poke.
His R is absolutely massive, especially on high attack-speed stackers, or top, and your jungler. The burst on it is also substantial, if you can afford to wait until you're melee range to use it.
However, since anything he can do outside of Q and E is basically auto-attack range, they often don't have the impact you need if you aren't ahead, especially since E is the only significant way he can interact with enemies, outside of relatively minor, but consistent DPS.
While I think he's fun, many people don't know how to utilize him well, making him underwhelming to many, even in his best-case circumstances. His rework isn't to make him more powerful, its to make it acceptable for him to be more powerful since there will be more interaction inside of his kit. His kit is actually really good, its just rather basic, and at the moment, under-tuned because of that. He's just too consistent to be allowed to be consistently potent.