The first big thing I notice is that its neck seems a bit short. He looks cramped in his space there  lol

The neck is definitely a bit short, but other than that I love the concept!

As with the other comments I agree the neck should be longer but apart from that it is perfect

Agreed with the comments above.

I do agree that the neck seems a tiny bit short, but I'm also wondering if it's just a perspective thing due to the turned head. 

If you're taking feedback for manes/tails, I'd definitely suggest the short tail being the typical appaloosa “Rat Tail”. 

Agree with Champagne on the perspective part and maybe a roached option to go with the “rat tail” or "broomtail" look? but also love the look as is!

i adore that it's keeping a similar pose to the old art!
agreed about the neck, also i think the left fore pastern may be a bit thinner than the rest? and the nose looks a little bit misaligned with the muzzle. there's not much i can comment on besides that, it's beautiful!

Hello!

The neck is a bit foreshortened, but it was definitely a bit too short for the angle of the head. I've made it a little longer. Thanks for pointing out the misalignment, @forgottenland! I've corrected it. The pastern may be still a bit thinner, but I'll keep the pastern and hoof sizes in mind when doing the lineart.

@Champagne, @DLE, The rat tail would be a really interesting touch! Thanks for the suggestion!

YES!

those changes did a lot! i think the legs are really even now and the head/neck area looks very balanced.
so sorry for not pointing this out before, but i noticed now the topline plunges a little dramatically? like the angle the withers make with the start of the back feels a bit harsh. looking at irl appaloosas, i do see a few have fairly steep withers but most seem to have a much softer angle to theirs. not experienced enough to know which is considered proper though haha.