Yorick's entire kit breaks and ceases to function if you miss your E, and E is VERY easy to miss.
So here's my feedback:
Yorick's E needs to be SIGNIFICANTLY faster casting, and needs to have a wider hitbox.
If Yorick's E misses (and with it's current cast time + travel speed + small AoE it's ... actually difficult to land) he has no mobility, his ghouls will fuck off and ignore you, your ult will fuck off and ignore you, you won't be able to land your W, and he has no CC. Effectively Yorick's entire kit is burned down to a single Q, which while early game is hella damaging, by mid-late game is simply not going to make you a threat.
Also I should mention because his E doesn't travel in a line it makes champions with gap closers/escape moves actually difficult to hit.
WORSE YET is Ghouls terrible AI has a tendency to jump at the target, run to get in to position, get maybe one auto off, then dance around like little idiots and never get another auto off.
The closest comparison I can think of is Illoai's E which:
A. Travels in a straight line. (Makes it so you can't gap close in to her to dodge it.) B. Comes out near instantly. (You can't walk behind her in the cast time...) C. Doesn't render the entirety of her kit useless if it misses. (Maiden of the- FUCK YOU IMMA RUN IN TO THAT TURRET.)
There are some serious problems with the kit (why in fuck's name does a split push MASSIVE COOLDOWN ultimate get targeted by a turret?!) but this is pretty much the one thing I'd legitimately like to see hotfixed. Yorick is in a very sad state right now, and rather than looking at his numbers (survivability...) I'd rather see his kit actually able to function consistently right now.