'Gentleman's Agreement' is pretty dated. It's not regarded as great cinema by anyone I know. And while we're at it...Johnny Belinda? :-) I'd take Schindler's List, Pulp Fiction or Fargo over those two.
From the perspective of now, Gentleman's Agreement is as dated as Bernard Shaw's "Arms and the Man". They seem dated because they attack attitudes that no longer exist (WASP country club anti-semitism, romantic pre WW1 attitudes towards war). But they are nowhere near as dated as, say, some Barbara Seagull 1972 hippie movie.