This is one of Laurence Olivier's few Shakespeare films that he did not direct himself, which is easily understandable: the Othello character demands so much almost superhuman exhausting energy in its fury and tirelessly constant acceleration, that directing it at the same time as acting it is almost impossible. However, Orson Welles did that, but his Othello film is more a cinematographic masterpiece than true to Shakespeare and the theatre - Orson Welles did as he pleased with Shakespeare's texts, while Olivier was always true to the original, and there is no abbreviation here. Maggie Smith is marvellous as Desdemona, and you feel her expanding with the development of the character, and it's also marvellous to see her so young. The most remarkable performance though is maybe Derek Jacobi as Cassio in his first major role, and he makes a splendid and lasting impression. The problem as always in every performance of "Othello" is the Iago character, as his evil is never given any motivation - he even ends by insisting that he will not tell anything and least of all any reason for his actions. That his only original motivation would have been an envy against Cassio seems a bit far-fetched and not very convincing - a small excuse for such tremendous consequences. However, it is inescapable that his character dominates the entire play, and it's a character impossible to fail at for any actor.
Olivier of course carries the heaviest acting burden and does it as usual with superior brilliance. To make this role he even worked on lowering his voice from his tenor to a baritone, and he also worked on making his diction sound convincingly negroid. His hair is totally convincing of a moor as is his entire character. He himself called acting somewhat bitterly, "a sado-masochistic ordeal", and you can feel that traumatic sense of acting indeed in his performance here. It's interesting to compare this film with that of Orson Welles, they are extremely different in character although it's the same play, and they complement each other. Olivier, though, is more a moor, while Orson Welles is more Orson Welles.