How did Saint Augustine react to Plato and Platonism?

There are a lot of parallels between St. Augustine and Platonism. Book 7 of Augustine's Confessions discusses his reading of the 'Platonic books', some books by the Platonists of his day.

St. Augustine found many truths about God in Platonist philosophy, but found that it was incomplete. His true conversion to Christianity showed him that in Christ, Platonism is completed and perfected.

Book 7, chapter 16 of the Confessions shows a great relation between Augustine and Plato's cave allegory, as well as the idea of Being versus Becoming.

Plato accepted Plato's philosophy above all other philosophies, especially above Astrology and the religion of the Manichees as mentioned in Confessions. The Platonist texts set him on the correct path in his search for God, as he began to see God as more eternal and infinite.

Platonism also helped Augustine realize that evil does not really exist as a substance - kind of like Plato's idea that all desire is desire for something good. Likewise, Augustine believes that evil only exists as desire for something less than God... kind of like Plato's lesser desires which are for anything less than the form of the good.

Basically, Augustine owes a lot of his personal philosophy to Platonism - he feels, however, that it is imperfect without a knowledge of Christ which he found in the Catholic faith.