(image from Wowhead) His sit animation makes me smile at least
Graves was recently updated with a model on the 6.1 PTR. It's uhhh interesting? I'm not sure what to think of it. It looks like a partial skeleton mixed with vines/roots, coffins and red crystals...? Not quite cute, not quite grotesque. I think this might be the first pet that I feel fairly indifferent about.
I suppose Graves would make more sense to me if I actually played Heroes of the Storm and saw it in its proper environment. I'll eventually have to do something Heroes related to earn the pet so maybe I'll see it soon heh.
Not much else was added/updated on the PTR, but one other notable thing is the Longest Day achievement change. Turns out it's not a very long day after all. In 6.1 you don't have to defeat all the listed trainers in a single day; you can earn it over time.
I'm not sure what prompted this change, but my best guess is that the achievement wasn't behaving properly for everyone. I vaguely remember reading reports about not receiving credit for a trainer or some other related issues. Perhaps Blizzard felt like the bugs associated with the achievement wasn't worth it, and decided to just drop the buggiest part of it. The removal of the "all in one day" requirement would make sense if that's the case.
Otherwise, I have no idea why the change. I don't consider it a difficult achievement. The trainers are static so you don't have to prepare for any changes each time you battle them and there are solid strategies out there for everyone to use or tweak to suit their needs. The "toughest" part of the achievement is the travel time between trainers IMO.
But I don't know. I'm sure the developers have their reasons, which they're under no obligation to share with us. I'll just be sitting here in the corner, speculating and brewing up conspiracy theories in the meantime. :P