A friend reminds me that homiletics is a physician-heal-thyself enterprise, so my critiques of student sermons are restrained. But not as restrained as those offered by
“a sexton at whose church theological students frequently did the preaching. He always had three stock answers when they asked with anxious curiosity how they had done. If they had done well he would reply, ‘The Lord has been gracious’; if moderately well, ‘The text is difficult; and if badly, ‘The hymns were well chosen.'” 
My criticisms are more direct, but not so much as those offered by Professor James Benjamin Green, who began teaching at Columbia Seminary in 1921. After one student’s sermon, he offered this analysis: “There were three problems with this sermon: first, it was read; second, it was read poorly; third, it wasn’t worth reading.”
Another student preached a sermon titled “The Double-Barreled Gospel” and received this feedback: “What a subject! ‘The double-barreled gospel.’ Unfortunately, neither barrel was loaded.”
 Helmut Thielicke in Gilbert Meilaender, Bioethics: A Primer for Christians, 2nd ed. (Grand Rapids: Eerdmans, 2005), 74.
 David B. Calhoun, Our Southern Zion: Old Columbia Seminary, 1828-1927 (Carlisle, PA: Banner of Truth, 2012), 356-357.