Yay, horse morphs!
I like how you have kept a very equine apperance with him, and the chunky legs are cute.
As the above comment says, his pose is a little akward and stiff, mostly in his lower body. He seems to be a little top heavy, which could be rectified by a more open stance and leaning his torso back some. Perhaps widen his hips a little, that should open the stance on it's own.
For human based proportions, he's well done (distnce from waist to top of head closely matches distance from waist to bottom of legs). However, what I have found in drawing equine morphics is that making the lower body slightly larger, and/or decreasing the size of the neck and head slightly, tends to make balance problems go away (or disguises them so well no one notices... ^^; ) Since he's a Percheron, the former would probably work best.
This is a very good start. I would really like to see more. shuts up now
Pretty good. Nice use of values, though they could be a bit more dramatic. laughs Then again, I'm big on dramatic lighting. ;) The one issue I see with this is balance. The pose is a stiff and ackward one. Try take the pose yourself and you'll see what I mean. People (or furries for that mater) rarely stand feet together like that. Most people spread they're legs slightly apart. It makes most sence balance wise. Try it. :) Heh, that's actuallu a good idea for any pic. Take the pose yourself and learn how it feels to see if it's doable. Hope that helps. If not, I'm happy to redline for you and explain that way. :)