I discovered this late one night on Turner Classics. I kept saying to myself "I'll turn it off as soon as it stops being funny", but needless to say I watched the whole way through.
I am a movie junkie but I had never even HEARD of this movie (or if I did in 1971, I forgot). It's worth watching just for the performance of Goldie Hawn as the tart-tongued ingénue. Her acting is a revelation in this movie. Yes, the script is sharp and excellent (when was the last time they made a Hollywood comedy with a smart script?) but her acting is extraordinary. I never realized how funny Goldie could be, and it makes her later appearances in roles such as Laugh-In and Private Benjamin a little sad. In her later career she is far too over-the-top compared to her minimalist, wickedly funny appearance here.
It's a pleasure watching the young Matthau, the great Bergman and the stellar supporting cast, but it's Goldie Hawn that will make this movie worth watching again.