This review reads very much like one written by someone who reluctantly is trying to find excuses to criticize it. Many of the things he says feel made up.
For example,
> Many of the questions I answered correctly were in areas that I don’t feel I understand well, but where I suppose I had drilled enough in the past for my procedural fluency to survive 20 years of atrophy.
The author is complaining that he felt like he should have done worse because emotionally he thought he knew it less than he actually did. This is an entirely fictional, made-up criticism. He obviously knew it better than he "felt" he did.
The entire review reads like this, trying to make up real-sounding criticisms that to me just don't make very much sense. The DAG criticism as well doesn't make sense. There is no "one way". The DAG approach probably works for many if not most students, but of course there are other students it won't work for. Exactly like how phonics works for many students but some need to be taught whole word reading. You can't criticize the DAG approach just because some students can't learn that way, but they have to pick one method. I would expect a teacher to have a better critcism than that.
He made the initial diagnostic test sound like it has a massive impact on what you'll study. It doesn't. Even if MA thinks you know a topic well based on the diagnostic test, that doesn't mean you won't encounter it again. He seems to have missed the fact that every time you answer a question, this affects the estimate that MA has about your comfort with one or more topics.
The excessive focus on procedural fluency is a reasonable criticism but, as I said in another comment, this doesn't bother me at all. There are plenty of other sources for this. And procedural fluency is a good enabler for developing conceptual understanding.