I loved watching reruns of this as a child. Bob Newhart has been my favorite comedian for as long as I can remember. What's the best about Mr. Newhart is the fact that even in his comedy routine he often times played the strait man which is exactly what he does on his shows. I especially love when he's talking to someone on the phone (like the cold open for the first season episode 'Not With My Sister You Don't) in a manner reminiscent of his great phone skits ('Abe Lincoln vs. Madison Avenue' is my favorite). I think anything Bob Newhart ever does is going to be absolutely fantastic (take his "Mad TV" skit...the otherwise mediocre show took on a whole new level of awesome).
Of course, while Bob Newhart was amazing, I think what I like most about this show was how great every actor on this show was, right down to his patients (Michelle, the girl with the nonsupporting father, was always a favorite of mine). It's a pity shows like this aren't shown on TV Land anymore.