I don't dislike Newhart but I don't get excited over him either. That being said, I do regard the man as a consummate professional and a higher talent, which he proves effortlessly with his appearance in last nights episode. The timing, the delivery made him stand out more than any of the core cast members IMO. Regardless of my interest, I can appreciate performances and performers like that. Old school right there.
Off topic but on subject, I was watching the movie Maverick (Mel Gibson/Jodi Foster) the other day because it happened to be on. There was a scene between Mel Gibson and James Coburn and just watching Coburn's style, mannerisms and charisma was a joy. This man at his age and with a non leading role IMO complete upstaged everyone else because he came up when actors gave performances. Even the way the man moved his hands while talking was strong. I compare that to Newhart's performance and there is just an aging quality of acting that you just don't see with the up and comers.