It does, unfortunately, have a bit of an "Old man yells at cloud" tone to it. And I don't see any solid evidence for his arguments beyond appeal-to-authority in that essay.
But he's done and continues to do a lot of good work. He helped found the Learning Sciences (an offshoot of cognitive science, AI, psychology, etc.) in the late 80s and early 90s. He continued and continues to do work in education, including founding experiential schools and writing books on education: http://www.amazon.com/s/?url=search-alias%3Daps&field-keywor...