A lot of valid criticism can be levied at the writing having lost some of its verve, but I think we tend to forget just how incredibly the production value of the show increased by that last season. Its arguably the most brilliant production quality of any show at that time. It's so amazing that even today, 30 years later, it largely still holds up.
By all rights, Sub Rosa is a thoroughly & rightfully derided episode, but just LOOK at it! It's a bloody stunning masterpiece of television production design. I mean, will you just LOOK at the f***ing composition of this shot!?!?!?!
Compared to this