I liked the fact that he was so complicated. He was insane, but at the same time much of actions involved plans as guided as Thrawn's. He was also sympathetic in one moment, and then absolutely terrifying the other. I could also never tell as well if he truly wanted an apprentice because he yearned to teach them, or because he yearned to rule over someone. Also I loved the cat-and-mouse game he had with Thrawn. It would have also been interesting to see how he would've handled a lightsaber, considering he thought them beneath him and only relied on the force.