How completely awful... (warning, spoiler)
The only thing I can imagine that would make this film worse is extended time. Wish I had that 105 minutes back.
FYI, in case you look here first to see if it's got a happy ending before you watch it, it doesn't! (I guess that depends on your point of view though--if you're all for meaningless sex with everybody and don't like romance or lasting relationships, it's a sweet ride.)
You spend the movie watching two characters get to know each other on a level they hadn't previously known another person, then Goldie Hawn inexplicably walks away at the end, and even more inexplicably, Peter Sellers gets a call the VERY NEXT MINUTE from a slutty au pair and he completely forgets all about Goldie.
Gag.