I have to chuckle about the casting of Omar Sharif as a Russian operative, and the way the movie complicates things by having everybody pretty much sleeping around with everybody else, but I think you hit the nail on the head with this one: slow burning but solid 70's-era Cold War spy drama with great acting from a bunch of fine actors and actresses. One instance where IMDB got it pretty much right on the nose with that audience rating. :)
RE: Film Review: 'The Tamarind Seed' (1974); Cold War Period Piece