Underneath all the stern and condescension, Mihawk's a pretty good fellow.
I appreciate it because it makes it more likely Zoro's and Mihawk's potential confrontation in the future won't be an antagonistic good vs evil fight, but rather a battle of honor, growth, and resolve. The man Mihawk first met was a frog in the well, too anxious to make his hopes a reality. He had nothing else on his mind but so. When they next fight, Zoro will have been the man who's defeated countless enemies, accomplished great deeds, protecting those most cherish to him, and a purpose beyond just himself. Mihawk has been as much a teacher as he was a rival to Zoro, and their final face off would be reflective of that.