Found it almost useless if going further than the very basics.
Being real noob here I'm loosing the grip at very first multiline examples with that going one slide ahead/back. And without 'human-readable' description of result of every code snippet...
Hey, it is just an introduction. I found she did quite interesting job there.
But, also, she gives at the end resources to learn it. What I didn't like is that she routes the people to the MDN (Mozilla Development Network) which isn't ever the best. Maybe best is W3Schools (and it has some errors as well).