In the books it is a dangerous Soviet intelligence agency that even James Bond has troubles dealing with and is itself based on a short lived real Soviet agency). Because of a new treat by SMERSH the MI6 tries to get him back into action (SMERSH is not transferred in the movies. The story is set long after the retirement of James Bond.
Firstly it has an awesome cast that can be described as some of the best and most acclaimed people in the industry back then and secondly it had countless troubles during production that harmed this movie (Don't know if the term development hell existed back then). Also it is a parody or spoof movie instead of a typical James Bond spy movie. It is the 1967 version staring David Niven as James Bond.
For clarification this is not the Daniel Craig James Bond movie from 2006.
