I haven't read Steve Keen's Debunking Economics, but, maybe I will, now that I am writing this blog.
Steve Keen is an Economist, and writes as an iconoclast and heretic, as much as a critic. He advocates for the out-party Heterodox against the in-group, Orthodox. It's a dispute I don't care about, to be honest.
Professor Keen does take seriously the fundamentals of economics, and especially the fundamentals as represented in the textbooks, particular the introductory, "Econ 101" textbooks. That's where my critique and his may intersect, since many economic arguments in the public political discourse derive their intuition and authority from Econ 101. The extent to which Econ 101 theory is faulty, or commonly misunderstood and misconstrued, is a real problem for the quality of the public discourse, as well as for Economics as a programme of academic research and teaching.
The simple fact that Economics can have a division between the "Orthodox" and the "Heterodox" may indicate that something is seriously wrong in the Academy. No academic discipline can usefully admit dogma to its doctrine. It may be useful, later, to explore a bit the epistemology of religion and science.