I always felt this movie was over-praised - I think critics were overwhelmed by the quality of the credits, and the concept of Garbo in a comedy, and the rareness of a successful satire on the Soviets. It's a good script, mind - just overlong, with a vaguely unsatisfying ending.
There is something a little yuck about the tough, no-nonsense woman turning to jelly at the sight of love. But the Soviet regime was pretty horrible, the love scenes are very charming, and I did like how Ninotchka sticks to her mission to retrieve the jewels because her people need it - she never stops being professional.
I adored the flirt stuff between her and Leon - he's a gigolo, basically, she's a hard arse, but she admits she finds him hot from the get-go - women characters in Billy Wilder films often had a strong sex drive. The Soviet stuff provides some wonderful one liners.
On the length stuff - maybe too much time is spent on the three support Bolsheviks, who all tend to blend into one comic character. Maybe we didn't need the late-in-the-day introduction of Ninotchka's flatmate in Moscow, Anna. I understood why it was all there, mind.
Razinin (the part played by Bela Lugosi) is an effective character. There's a reactionary butler - a very common device from films of this period (maybe to make filmmakers feel better about having them?)
I'm also so relieved all our heroes wind up in Instanbul at the end and not Paris .- if they'd stayed in Paris they would've been shot! And unlike many romantic comedy pairings I could see Ninotchka and Leon making a go of it because she's so sensible she'd ensure any business they did was a success.
Many fine examples of screenwriting in this script - notably a use of Ninotchka's attitude to a hat, to demonstrate falling in love (disdain, disdain, putting the hat on....)