The focus on actually building something, obviously.

They are mindful of organizing the pieces of things that matter: courses are divided into meaningful chunks that assemble a coherent set of elements. This is the hardest thing to do well, in my opinion. (Would be interesting to hear your thoughts on what are meaningful chunks in the btc ecosystem -- transactions is one, clearly. What are others?)

Nice interaction elements to support realistic learning, e.g., at relevant points the window will show a badge linking to relevant things in the syllabus, annotating what the lecturer just said, providing context, etc.