One must travel back to the 19-Sixties to appreciate 'Fantomas' to the full.
In those days English James Bond was taking off with his second or third film, creating a hype that is exceptional in film-history right up to this day. According to the customs back then, the French came up with 'Fantomas', providing a counter-weight that made considerable impact. However, in the long run James Bond has lived on while Fantomas is by now clear history.
Watching this film for the first time since 1965 or so, one must conclude that 'Fantomas' makes a comedy, as well as a clever persiflage of the contemporary James Bond (performed by Sean Connery). Shot with the techniques available back then, catching well-acted roles by prominent French actors and actresses of those years.
For those who were not around in 1965, I fear that 'Fantomas' has not much to offer. Knowledge about the mid-Sixties is necessary to understand this film to the full.