Very infrequently does the opportunity to play an acting legend present itself . More seldom when the actor is one you have been compared to your entire career.
Kenneth Branagh has been steeped in Olivier's shadow for years, despite that no men have done more to revive Shakespeare than Branagh and Olivier. Both, well versed in stage acting, crowned with honors, etc.
Branagh is no stranger to adapting Olivier's work—he remade Sleuth in 2007, as well as wrote and directed adaptations of Henry V and Hamlet—so playing the man may have been too tempting to pass up. Few men are as decorated as Laurence Olivier (10 nominations, 3 Oscar wins) and playing Sir Laurence may finally be the push for Branagh to win the gold statue himself.
Branagh plays Olivier as a man of contradictions. He desperately wants to be as big a star as Monroe, but his selection of roles makes that transition almost impossible. He nails the voice, mannerisms, and the odd mix of modesty and arrogance that compelled Olivier to rage against others like a third world dictator. With that said Branagh still plays him as the talented man he was. And more importantly, with authenticity.