Claudius was not evil, but rather a human being surrounded by certain flaws along with his life.
Administratively, the balance of his reign was positive. He extended the frontiers of the empire, restored the rule of law, and imported corn when food was scarce.
However, he had always been thought to somewhat dimwitted. During the reign, if Caligula he developed a reputation for being an alcoholic. He did not have good experiences with women. He ended up getting married 4 times. This caused him a personal deterioration. At the end of his reign, he began losing trust in some of his affiliates. This led to him ordering many executions of people who apparently were conspiring against him.
He is thought to have been killed by his last wife, Agrippina. Who supposedly fed him with poisoned mushrooms.