Quadropedavia! Keeled sternum (youd need a big one to attach the kind of flight muscles that would get this guy off the ground), modified scapula. My pegasus are fully feathered, including a ruff around their necks into which they can tuck their front feet to make them more aerodynamic. They have a feathered tail that acts as a rudder, although it does have a bone in it. Their feathered manes also help them maneuver in the air and are used socially for signaling mood. They have hollow bones and a birds complicated lung system to get enough oxygen for those flight muscles. They have a cloaca. They lay eggs. They are technically monotremes.
Things I dont like: I think the skull should have been smaller, and it should look lighter than a horse skull (which it doesnt). I think I should have made the spine longerlike a crane as opposed to a song bird. He looks too bunched up.