Hmm... I'm going to critique a couple little things.
The rider looks like they're puckering their lips out like they're going to give a big ol' kiss to somone.
The rider's arm is also insanely skinny. Like there's a jacket wrapped around their bones.
The rider's helmet looks like it was shoved all the way down on top of their skull or like they're wearing a helmet skull cap of some sort.
The horse's near hoof looks more like a side view hoof.
The horse's far hoof looks more like a fron view hoof.
The horse's ears are on two different levels of the head...
The horse's elbow is a bit funky. It looks as is it has no shoulder... It also looks too geometric.
It looks like the horse has no neck. I know that 3/4 view horse necks are insane to try and draw so... I'm just saying kudos for getting it that close. I would have failed and given up.
Now by critiquing, I am in no way saying your art stinks or anything, I'm just pointing out minor flaws. That is it.