Underrated; terrific Matthau and Pat Boone!

I agree with you, this film has never been fully appreciated. One must first look at it IN CONTEXT; that period in the mid sixties when frank discussion of sexuality and adult situtations (or even bad language) were not permitted on the screen---but the swinging sixties and the sexual revolution were just around the corner.

George Axelrod's play had to by necessity and the hollywood standard of the day be sanitized. The screenwriter had to rely on double entendres, innuendo and wit to convey the adult situations floating just beneath all the surface fluff.

When was the last time Debbie Reynolds came off as SEXY and a bombshell on screen?

Pat Boone was actually FUNNY poking fun at his own homespun image

Walter Matthau was hilarious as the skirt chasing producer who shot charlie. Check out the scene where Debbie Reynolds as "charlie's widow" confronts Matthau. The dialogue along with the tacky accent is too funny.

The dialogue between Tony Curtis and Debbie Reynolds as "Charlie" was--if you REALLY pay attention---witty and wicked.

The scene at the beauty salon where Debbie Reynolds passes herself off as "Charlie's Widow" threatening to write a tell all novel then proceeds to blackmail all the Hollywood wives Charlie had an affair with, rivals anything you've seen on "Sex and the City" or "Desperate Housewives."

If you strip away the sparkling dialogue, big Hollywood names and great sets, the story in and of itself is very dark. George Axelrod had some pretty cruel things to say about and against women. Keep in mind that he also wrote "How to Murder your wife" another vehicle (also with Tony Curtis, co-starring Verna Lisi) that at first glance appears to be nothing but comedic fluff but, underneath lurks a very cynical and cruel view of marriage---and women.

This was the era of big budget Doris Day films, which were sex comedies diluted and made palatable with sparkling and witty dialogue, sumptuous costumes and great music (lest you forget Doris Day was the biggest box office star of those years.)

It would be unfair to judge "Goodbye Charlie" by the same standards you would apply to a modern day romantic comedy. In 1964 they had to make due under many constraints but still managed to produce a funny film.