TL;DR: one of the best deals I ever bought on Appsumo.
Try for yourself.

As a freelance developer I usually struggle thinking in terms of design and UI/UX, often falling back to ready-made frameworks and design systems (read: bootstrap, material, semantic, etc).

I just completed design basics and I already understand why and how some design systems work. Also, I'm very happy with it because I can already see how i can improve my production websites.

Strong pros:
* gaming system is amazing, i love it
* learning material is easy and clear
* lots of valuable and useful insights
* unmatched price / value

Could be improved:
* timer for non-english speakers (may be a little more merciful, btw I'm Italian)
* mobile design for exercises / challenges (good as it is, imho may benefit by being "compact" or introducing a toggle for it)