If you don't use the same name in the variable/functions/arrays as the ones used in the solution, your work worth nothing. This is very sick!
Besides that, it was decent or common sense to be written clearly to each exercise, click first hint to see how we named the variables or the functions or so on so you will not get frustrated that you wrote wrong when actually you wrote well.
Huge knowledge goals between the exercises. You find yourself in exercises asking you to use knowledge which was not previously explained. I am not learning first time, is just recap after some years and I find very difficult and like fall from the sky some of the questions/exercises encountered.
The so called "catalog" has on the first rows the most complicated skills/project. Instead of having on the first line the programming languages and the things like make a website, make an interactive website which combines and require knowledge of several programming languages should go after. Not the other way around, the way they are currently. The should be displayed in a logical studying sequence.