Is it still too soon for Nunu buffs?

Nunu has been sitting at the worst win rate out of all champions in the game since his rework (in most tiers). Why is Nunu doing so poorly up the ladder and what could be adjusted to fix him? Is it simply that people aren't used to his kit yet?

I've been playing him and haven't had a lot of problems, but he really feels like he lacks any meaningful damage outside of his fully channeled ultimate. His cooldowns are quite long even with maximum CDR, which is really punishing. Many times I'll use his W to snowball out of base, but then it's still not up again when I'm needed to gank for my team.

This is my favorite rework Riot has ever done, and it makes me sad to see Nunu doing so poorly despite getting such an awesome kit.