Everything you love about Sean Connery's stint as James Bond is in this episode. The stunning femme fatale, the beautiful lead female, the unrepentant bad guy, daring-do and a little sexism.
This episode perfectly highlights the characters Napoleon Solo and Illya Kuryakin. While Napoleon doesn't skew the flirting with the ladies, and appreciatively looking at their backsides, Illya is closed off, almost emotionless. Otherwise, they're manly men carrying guns and talking with their fists.
This episode features a zany plot, involving fear gas, a mountain fortress and all sorts of stuff. Quite frankly, this episode is something I like to call 'cracktastic': Explaining what the episode is about is almost as much fun as watching it. This is basically an early James Bond movie wrapped up into 45 minutes.
The acting and really just everything about it is typical 60s; sometimes stilted and overtly dramatic, but a joy to watch. If you want to see and understand television from the 60s, you need to watch this episode, and you need to watch this show.