And rated 100% at Rotten Tomatoes, and 90% liked it.
Here’s the 1952 review from the New York Times:
Those who may fear that the old days of silken spy films are as dead as the gone days of diamond tiaras and princely diplomacy can now settle back in the comfort and the tingling satisfaction to be had from Twentieth Century Fox “Five Fingers,” which arrived at the Roxy yesterday. For here, in this literate entertainment Joseph L. Mankiewicz has made with a cast that might well have been recruited at an embassy function in pre-war Berlin, is as dandy an espionage thriller as ever went through the polished hands of a Grahame Greene or an Alfred Hitchcock—or for that matter, an E. P. Oppenheim.
And what’s more, added to the relish of this spicy adventure that is played in a particularly suave and crafty manner by James Mason in the central spy role is the fact that the story of it is almost a literal account of a fantastic piece of spy work that was accomplished in Ankara, Turkey, in 1944. That story has since been recounted by a former attaché of the German Embassy there in a book called “Operation Cicero.” It is this book by L. C. Moyzisch upon which the film is based.
And unlike modern movies, the twist ending at the end actually made sense of the biggest unanswered question I had while watching it.