What is Platos theory of Forms? Is it true? Does Plato state any good objections to it?

Jostein Gaarder best describes Platos theory of forms as another realm of reality which holds the eternal and immutable patterns behind the various phenomena we come across in nature (Gaarder, Sophies World, p73). Plato argues that knowledge of the forms can only be achieved by letting go of the senses and using intellectual reason. He believed that the senses did not provide true knowledge as they are unreliable therefore everything in the material world, which we perceive with our senses can be said to be false….(short extract)