According to this site, Uncle Norm did many things right. He used the right formula,
"The Man from UNCLE is a great example of episodic television — few plot threads ran longer than a few episodes. Despite the constant formula, each episode was fun and the writers could embroider the structure with whatever they wanted. That means that there were robots, fear gas, and tiny deadly bees. Yes, things got silly. The innocent civilians made things easy to explain things to the audience. Plus, it put a nice lampshade on the insane world of international espionage."
He used the right partnership -
"The interaction between Solo and Kuryakin is the best part of the series. Given the formula, you’d think that the two would spend a lot of time rescuing pretty innocents. Which they did, but they spent as much time, if not more, rescuing each other. They rescued each other a lot. Enough that you started to wonder how good at being spies they really were."
Then there was the tech and UNCLE itself.
What I would like to know is what has made MFU stay indispensable in your heart. All of these are fine points. I think it was because the show didn't take itself too seriously. More times than not, it was just plain silly (especially after the first season). I think it was when it decided to turn so serious that it signed its own death certificate. We didn't want serious espionage, we wanted MFU.
What say you, cousins?