Funnier than anything that comes out today, but not as good as Monty Python
The CSM review for A Fish Called Wanda is a bit harsh, both in terms of how appropriate the movie is, and in terms of how good it is. To start with, it's a very funny movie with great performances by Kevin Kline, John Cleese, and Michael Palin. I wasn't so big on Jamie Lee Curtis, but she didn't do badly. I thought it was a very clever, witty film and not the bland comedy that the review here seems to convey.
As for appropriateness, well, there is a good amount of language and sex, but the sex isn't explicit. At one point John Cleese is undressing (a very funny scene) but you don't actually see anything, except for maybe his bare behind. Honestly, I think this is appropriate for mature 14 year olds and up.
Violence (PG): Charecters murdered, charecters rob, and try to kill an old lady.
Sexual Content (R): Jamie Lee Curtis does a lot of it with her "so called brother" Gay jokes.
Language (PG-13): Lots of mild profanity.
Drugs/Tobacco/Alchohol (G): Jamie Lee Curtis drinks often.