Complex sentence: Speer characterised Morell as an opportunist who, once he achieved status as Hitler's physician, became extremely careless and lazy in his work; one who was more concerned with money and status rather than providing medical assistance.
Split into simpler sentences: Speer characterised Morell as an opportunist, who once he achieved status as Hitler's physician, became extremely careless and lazy in his work. He was more concerned about money and status rather than providing medical assistance.