You did a pretty good job of reproducing your reference, but the reference itself is . . . problematic, and you've exaggerated some of its bad points.
There's no easy way to say this, but you exaggerated the pectoral muscles too much, to the point where they no longer entirely look like muscle. You might have a cow here rather than a bull.
It's the combination of the way they stick out to the sides and how the highlights work. (Your reference is almost but not quite as bad.)
Horns should curve in the same direction—right now, it looks like one of them is glued on backwards. Both tips should point up unless you have a really good reason for doing otherwise. Check photos of real bulls. Again, this is an error carried through from your reference.
The arms seem to be different sizes, and I think the left one (the one straightish at his side) may be too short. Stand up and hold your own arm in a similar position and see where the hand falls in relation to your waist and thigh. (Your reference has the arm further out to the side than you do, which might account for the discrepancy.) The way you've handled the shadow on the left arm isn't right either—you've got this highlight on the underside that doesn't really make sense, and you're shadowing the creases between the muscles more darkly than the bits that actually have shadow cast across them. The other arm is better in terms of shading—it's dark, but it isn't as confusing.
Reproducing the teeth was maybe not such a good choice—they're relatively larger here than in the original, and stand out a lot more than they should. The result is kind of bucktoothed/beaverish.
Left hoof looks a bit stubby/truncated.
I'll assume the apparently four-fingered hand was intentional (no real reason a minotaur should have five fingers).
Again, you did do a pretty good job of reproducing your reference—the 3D model shown in it is just weird. And I maybe emphasise realism a bit too much sometimes.
