Interactive numbers in the UI: seriously awesome. LOVE that they did this. Hopefully we'll get live updates to code in more systems, it's wonderful. Lack of a 'course' to go through: ? I have no idea where to start. Nor can many of these be applied outside of the little editor with the 'tutorial'. Elsewhere, KA has a nice 'do this, then that (or that )' set of branching paths that give you a reasonable path to take.…
I don't see a problem here. I really like the playground feeling it has all around. Maybe I'm biased, but I prefer "pick the one that appeals more to you" style.
I'm not convinced that they develop great foundational knowledge about a system; they tend to favor quick, narrow dives (to any depth), rather than mucking around in all the boring bits that actually make the whole system. Great for getting the gears turning and keeping interest levels up, not great for full comprehension.