He has generally been regarded as a very weak emperor; but he has also been lauded for his sincere devotion to peace and common good.
From Pope John Paul II's beatification homily:
The decisive task of Christians consists in seeking, recognizing and following God's will in all things. The Christian statesman, Charles of Austria, confronted this challenge every day. To his eyes, war appeared as "something appalling". Amid the tumult of the First World War, he strove to promote the peace initiative of my Predecessor, Benedict XV.
From the beginning, the Emperor Charles conceived of his office as a holy service to his people. His chief concern was to follow the Christian vocation to holiness also in his political actions. For this reason, his thoughts turned to social assistance. May he be an example for all of us, especially for those who have political responsibilities in Europe today!