Plato was an astounding advancement over the theories that had been present in Greek Philosophy before his time. He was certainly closer to truth than many philosophers operating without the guide of revelation. However, Plato’s philsophy is generally incorrect in most areas (although more correct than many other theories). Many Catholic philosophers and theologians have tried to work with his theories as much as possible and take whatever was good from them, but it has been proven to be a dangerous exercise, even for great saints like St. Augustine.
The real master of philosophy in the ancient world is Plato’s student, Aristotle. The improvements and corrections that Aristotle made to Plato’s efforts are astounding, and Aristotle was ultimately correct on the vast majority of his theories and systems of logical progression. St. Thomas Aquinas, who is the Catholic Church’s pre-eminent philsopher (as stated by many popes and made into official policy by Pope Leo XIII) is essentially just adapting Aristotle to Christian revelation.
Plato is certainly worth reading. As has been stated, he is one of the most influential philosophers in history, but as a Catholic, I would advise caution in accepting his conclusions. Aristotle is a much safer read, and is even ultimately more influential for Catholic philsophy and theology than Plato is.