This movie was one of a handful that actually caused me pain. It might be enjoyed by anybody who thinks that it would be funny to see his/her mother in a crowded discotheque full of people half her age "inventing" some totally ridiculous dance in a completely misguided effort to be "hip" (in the parlance of that age). To see Ingrid Bergman stoop to such a pitiful performance on the disco dance floor was hard to watch. I was embarrassed.
To make matters worse, the music in the disco was not realistic at all - it is the bogus idea of some Hollywood director about what pop music was like at the time. That is always a total embarrassment in most films of that era - the ersatz music is canned and bears only a painful, passing resemblance to the music that was actually popular in the 60's.
Mathau is hopelessly miscast as some kind of ladies' man; he just looks lecherously grotesque. Hawn's wide-eyed innocence is just too silly. The handsome neighbor in her apartment is portrayed way too earnestly and seriously. He seems like a Brady kid who got lost in this farce. Painful, pitiful mess.