Thank you thank you thank you for being critical! I always learn and grow from honest reviews.
I'm of the opinion that the hoof (lifted) is proportionate to the rest of the leg. Admittedly, I was having a LOT of difficulty with horse anatomy, and in fact, I'm still unsure about this unicorn's skull shape. The stage-right/it's left legs I'm pretty uncertain about too...Using Google Image, I was even having a rough time finding a horse that was doing similar body language, so I just kinda winged-it. In my research, though, I found all kinds of different horses that were actually way different shapes from others...so, I'm going to lean in a direction like "What I've drawn here is a fictitious Blood Unicorn, so it's structured a little beefier in some places."
Thinkin' of it akin to some sort of a super war-horse that's meant to lug around a sorcerer weighed down with armor and a heavy sword. :D
HAVING SAID ALL THAT, I totally agree that parts of it's leg are a little too human-structured, and my eyes are drawn around where our calve muscles would be behind and around the unicorn's front knees (write/draw what ya know, I guess). If I could hone and refine this further, it would definitely have to be an effort into making it more realistically horse-like. I completely acknowledge that drawing realism onto animals I don't draw often...no, EVER...is absolutely a weak point of mine that I should practice more upon. But hot damn, am I proud of this practice :D
Again, I'm REALLY, REALLY appreciative of the advice. That's the kind of stuff I need if I'm ever to grow! Thank you for the praise as well, that keeps me goin'.