Very interesting question and the answer is rather long and complex, but here are a few ideas to get you started.
Plato saw Philosophy to be opposed to Poetry and Rhetoric. In fact, he alludes to the "ancient quarrel" between these two sides, as he saw them. One of the ironies concerning Plato is that despite his unremitting hostility towards poetry and rhetoric, he is famous for his own poems and rhetoric. Go figure!
Plato, in his work, Republic, attacks viciously the poetry of Homer and those who support it. He addresses his remarks at the "praisers of Homer who say that this poet educated Greece, and that in the management and education of human affairs it is worthwhile to take him up for study and for living, by arranging one's whole life according to this poet”. Plato seems to be setting himself up against the entire worldview that Homer and his followers have created and sustained. He argues that the influence of poetry is pervasive and often damaging, and that the ideas it presents about nature and the divine are often mistaken.
Although Plato acknowledges the usefulness of poetry, in education, in civil celebrations etc, he regards it at all times with suspicion. Although he recognises poetry is a vital and necessary part of human society, he sees it as a mark of humanity's fallen state. Of course, his remarks must be read within the cultural framework of Plato's time, where the dissemination and spread of poetry was very different.
Like the other answer, in some ways Plato was opposed to poetry. In particular, he did not like the mimetic aspect of poety - namely that poetry imitated life. This aspect of poetry was seen as opposed to true reality. Plato had a robust idea that what one really needed to know was the eternal forms and one could only gain this knowledge through dialectics, that is, philosophy. This is why Plato banished the poets from his ideal Republic. However, to say that Plato does not use poetry in his writings would be wrong. Any platonic scholar would tell you that Plato uses plenty of poetic forms and devices all throughout his works. I think he does this, because he sees himself as a true philosopher. True philosophers are not really prone to the dangers of poety, because they have been trained in the school of philosophy.
Now, do I agree? No. I love poetry. In addition, I think one can argue that poetry gives a person a better view of reality as it is able to capture the essence of certain things.