For a start, while I love Larry David when he plays Larry David, I seriously doubt whether he can play anyone else. He is a Jewish New Yorker trapped in the body and mind of a Jewish New Yorker. Fortunately, the third most famous man to answer to that description is given his own skin by the first. What doesn't work is his notional day job as a nuclear physicist, but strip the script of the occasional quantum reference and nobody would miss much. Better to have made him a retired comic writer and be done with it.
That aside, Larry David plays Larry David and plays him well. He gets to deliver some Woody Allen lines that are more thought through than his usual Curb Your Enthusiasm improvisations, but they seem no less spontaneous; Larry's sounds like a stand-up even in the most mundane of conversations, and while he doesn't have the genius of a near Nobel prize winning scientist, he does have a knack at gnawing at the bones of a conversation until they miraculously regrow meat.