Looking at some of the other comments, not everyone is in agreement here, but I have really liked "Les Visiteurs". The original is so good, its a pity they had to spoil with the Americanized version - 'Just Visiting' - which is at best an insult on the intelligence of the American viewing public.
For us that do not understand French, they have done a tremendous job with the English subtitles (translating a kind of 'medieval' French into a comparable type of old English modern swearwords included). In fact, the job is so well done, that we had a lot of laughs just by comparing the film's verbal antics to the translation. Even though I do not speak French myself, it is quite clear that a lot of effort had gone into this. Sometimes the conversations are fast and furious, so it's worthwhile to see the movie a second time. Even on the second pass, there was a lot to laugh at.
This is meant to be slapstick and the story is a total farce, so it's hard to see why some viewers apparently expected more. I thought it was well done, and very well executed. Even though this whole thing is intended as a joke, the reactions of the medieval guys are quite believable.
The movie is a blast!