As others have commented, this is certainly light entertainment, not heavy on elaborate plot lines. I actually saw this movie today on a flight from Japan, and found it delightful. It certainly is a film that was pitched to a French Audience, tossing in simplified bits of Japanese pop culture (Witness: I have never encountered so many Japanese that could speak French, as in this movie). Nevertheless this is what I liked about the movie:
1. The interplay between Fiorentino (Jean Reno) and his sidekick Momo (Michel Muller) was consistently humorous throughout, with Muller delivering the punchline, and nearly upstaging Reno throughout. My favorite scene is when Fiorentino is eating generous gobs of Wasabi (hence the name of the film), and Momo, not wanting to be outdone by his mentor, nearly gags to death on the stuff. I was laughing out loud -- maybe because it reminds me too vividly of the first time I ever ate sushi, and nearly died doing the same thing as Momo!!
2. Ryoko Hirosue, who plays Yumi, the previously unknown daughter to Fiorentini, is one of the current hot young faces in Japan, and has appeared in many TV dramas and movies. She certainly provides all the eye candy I could ever wish for in this film. But I must admit a certain new found-respect for her acting abilities, as she pulled off her lines in French flawlessly, while maintaining her trademark cuteness and capturing the carefree attitude of today's Japanese youth. She provided a foil of a different sort for Reno, her bright colors (pink hair, pink everything) offering a striking contrast to Reno's darker, demure look.
The Yakuza were portrayed as mindless goons in this film, and there are certainly better films out there if you want to know more about Yakuza, but it appeared that they played their role, which was to showcase Reno's machismo, in a humorous way, something along the lines of Jackie Chan films -- they are more like props in the film than anything else.
All in all, I was entertained by this film, which is all I was looking for during my 11 hours crossing the Pacific.