First of all, I think I'll add a short introduction to Feluda stories. Among over two-hundred novels and stories Ray had written especially for teenagers, the detective stories of Feluda are by far the most popular. With calculated amounts of wit, suspense, action and humor, the stories are considered classics of modern Bengali literature. So it was not surprising that he would make one of them for the screen.
As a book, "Sonar Kella" is one of the all-time bestsellers. Now I have seen the film about ten times and what fascinated me is how Ray changed the whole structure of the book while making this film. The novel is a fantastic detection story with sharp plot twists. But Ray thought the concept of detection as a theme in this film will not make the viewers see it more than once. So he makes it more like a modern thriller -- he showed the crime and criminals at first and now the theme becomes how Feluda unfolds it. That's why crime and detection is not the only theme of this film. There is plenty of humor and excellent visionary of Rajasthan too. Ray primarily directed the film to his readers but also made sure it satisfies all kinds of audience.
Another point I want to make: if the viewer doesn't know Bengali and relies on subtitles, he/she misses a good percentage of its fun. That part lies on its extremely witty screenplay where often Ray literally played with the words. Among the actors, Soumitra Chatterjee is quite good as Feluda, at least he was the best for this part in that time. Santosh Dutta virtually created the character of Jatayu. It became his trademark role. And one must mention the flamboyant and passionate performance of Kamu Mukherjee as the villain Mandar Bose.
The film features all of Ray's trademark styles -- in artwork, in script, in the camera angles and original music. And it remains an all-time family classic in the history of Indian cinema.
