It’s obviously a personal preference in the end. He has an excellent voice. His cover of “The Christmas Song” is one of the best I have heard.
I think I might have liked him if “O Tannebaum” had not been the first thing I ever heard from him. His voice was good, but his delivery was very affected. I suppose that really is a matter of personal taste. Now that you mention it, “The Christmas Song” is another Christmas song that I find rather annoying, no matter who sings it. Maybe I need to listen to some of his standards to make a more informed judgment.