My take after playing a few games on Yone and playing several against him.

Yone has too many ways to interact with his opponent while limiting their ability to interact with himself. This doesn't mean he is unbeatable, but gah, really annoying champion to lane against unless you have the counterpick and his kit naturally makes him a late game menace.

At a minimum they need to make the shield gained from Spirit Cleave only occur on hitting champions as this would allow you to get more chip damage on him.

At maximum they need to remove the cleanse effect he gets by snapping back to his clone after using Soul Unbound.

I also don't like the fact that he can hold Q3 and ult, but if they made the other two changes I think this ability is probably still fine (still provides high highs when played correctly).

Honorable mention to the fact that he does mixed damage so itemizing against him is somewhat problematic.