For beginners the learning experience is a bit dull, a lot of videos, there should be more specific exercises, lots of small exercises to train specific things with pre-populated data.  

Like there is in the becoming a developer path but a lot more of them.
Please have a look at the Salesforce trailhead, and the exercises they make a user go through to get the points (more points if you do it right the first time as well!).

Many coding academies have challenges by making copies of airbnb application or something like that - that would make the experience more rewarding.
Note: there should be a video of someone making the exercise (ie. showing the way in case the user gets stuck in the exercise if they are longer challenges). 

It would help someone going through the whole OS ecosystem and the steps needed to be done for certain,  otherwise I listen but then I don't get to play (reinforce the learning).  

For training purpose it would be nice to take a test exam before going for the real deal :)

This is a good idea :-)

Good idea.

Yeah especially for the higher level exams it would be nice to see a test exam with a small sample of questions.

great suggestion!