The following is an excerpt from the Catholic Encyclopedia article about Blessed John Duns Scotus, the "Subtle Doctor," a doctor whose influence grows upon me by the month.
Scotus is a genuine Scholastic philosopher who works out ideas taken from Aristotle, St. Augustine, and the preceding Scholastics. He is universally recognized as a deep thinker, an original mind, and a sharp critic; a thoroughly scientific man, who without personal bias proceeds objectively, stating his own doctrines with modesty and with a certain reserve. It has been asserted that he did more harm than good to the Church, and that by his destructive criticism, his subtleties, and his barbarous terminology he prepared the ruin of Scholasticism, indeed that its downfall begins with him. These accusations originated to a great extent in the insufficient understanding or the false interpretation of his doctrines. No doubt his diction lacks elegance; it is often obscure and unintelligible; but the same must be said of many earlier Scholastics. Then too, subtle discussions and distinctions which to this age are meaningless, abound in his works; yet his researches were occasioned for the most part, by the remarks of other Scholastic philosophers, especially by Henry of Ghent, whom he attacks perhaps even more than he does St. Thomas. But the real spirit of scholasticism is perhaps in no other Scholastic so pronounced as in Scotus. In depth of thoughts which after all is the important thing, Scotus is not surpassed by any of his contemporaries. He was a child of his time; a thorough Aristotelean, even more so than St. Thomas; but he criticizes sharply even the Stagirite and his commentators. He tries always to explain them favourably, but does not hesitate to differ from them. Duns Sootus's teaching is orthodox. Catholics and Protestants have charged him with sundry errors and heresies, but the Church has not condemned a single proposition of his; on the contrary, the doctrine of the Immaculate Conception which he so strongly advocated, has been declared a dogma.
You can learn a great deal more about the Doctor Subtilis by following The Smithy, an excellent but quirky blog (if you're not seriously into Scholasticism!) that I have been remiss in following the past few months.