Julius Caesar is a good movie, worth seeing, but it's difficult to say exactly why.

It survives a deadweight glossary of Hollywood stars--including Marlon Brando, John Gielgud, James Mason, Edward O'Brien, Deborah Kerr, and Greer Garson, a number of them wasting their talent and experience on bit-parts and walk-ons.

It has to survive disillusioning bursts of canned applause, poorly spliced film, a faulty sound-track, paper mache countryside, and a disconcerting propensity on the part of the cast to get that gleam of timeless monument as they're about to mumble a famous passage.

It suffers from a Julius Caeser about as imperial as a bourgeois Huey Long sans pitch-fork and red neck. From a Marlon Brando rendition of Mark Antony which turns him into a thick-skulled gladiator with Actor's Studio eyebrows who reads his lines like Bartlett quotations.

That would be enough, but there's more. The sound-effects man was obsessed with reducing everything to tape--including the subtle squish of a knife in the belly. Edmund O'Brien and Brando confuse drama with intensity and emotion with shouting. And the producer staffed Cassius's band of conspirators with film lot extras noted chiefly for Grade B gangster movies and smoked alfalfa sagas--making it difficult to take their pentameters with the proper seriousness.

Nonetheless, it it a good movie. Good because Gielgud as Cassius turns in a tremendous performance, because Mason as Brutus beginning with the assasination--is excellent. On these two performances, a few good camera angles, and fine musical background, Julius Caesar's success and entertainment value depend.

And, of course, it's a competent script.