When I saw the first episode, I cringed a bit. How they had aged (not really Collier though) and how the humor was not like it used to be.
But as I watched more of the episodes, I enjoyed them more and more.
This is a series about Duncan, Paul and Dick...grown up. Not young medical students/doctors having fun, doing pranks and chasing nurses. But middle aged men with responsibilities (again, except Collier - to a point).
I would say the last 4 episodes are the best ones; the funniest and - gasp - the deepest as well. Dealing with interesting ideas about middle aged men and how they handle them in different ways.
I think when I was young - when I watched the first series (Doctor In The House, Doctor On The Go, etc.), I think I would have liked those better. More fun, less serious. But now that I am middle-aged, I think I like these ones better.
I get the impression this series did not do well when it was released (I live in Canada). Probably for similar reasons I was put off of it when I first saw it. Which is a shame....because it really was a fine series. And - IMO - a worthy way to end the run of the likable trio of Duncan, Paul and Dick.
My best advice to watching this series is - don't expect the shows to be as silly/slapstickish as the originals. Expect something a little more serious...but still fun.