Especially his solo chord melody arrangements. They are so unique and creative. He's a monster!
My grasp of the technicalities is limited in the extreme (I'm no musician) but there is definitely something very personal about the way he approaches them.
IMO his classical sensibilities play a large part in making his approach unique. To call his solo arrangements "chord melody" really doesn't do them justice. He effortlessly goes between chord melody, bassline comping, and very subtle combinations of all three elements (chord, melody, bass). All this wouldn't mean all that much if the music wasn't so good. He's monster, but his arrangements and compositions are interesting. That's what keeps me coming back.