In his dialogue Phaedrus, Plato retells an Egyptian myth

In his dialogue Phaedrus, Plato retells an Egyptian myth about the origins of writing. In this myth, the god Thoth proudly shows off his new invention (writing) to the king of the gods, Thamus. The latter, though, is more worried than impressed. He warns Thoth that instead of using writing to aid their memory, people will use writing as a substitute for remembering things. Thamus even suggests that writing will help hucksters pretend to be wise.
In Plato’s time, most people didn’t know how to read. As such, people developed elaborate systems of memorization. What are the advantages and disadvantages of needing to memorize things and pass them on orally? What are the advantages and disadvantages of being able to write things down?