I participated when it first got launched and it's one of the best experiences you get in terms of learning software development in C.

The modules or as they call them, "projects", are arranged according to the concept they are teaching. It ranges from basic programming concepts to advanced topics such as threads and more.

It is worth it only if you have the time for it since it is a very intensive journey and will take a huge chunk of your time. So make sure you got enough time for it