I have been a long-time customer of MineAcademy (beginning from when the project was still called SpigotCourse!) and I can honestly say that Matej is a fantastic teacher. Learning with MineAcademy has been more efficient than looking for resources myself on YouTube or Google. I was initially disappointed and concerned about the the heavy reliance of the Foundation library, but MineAcademy along with self-learning and dedication has allowed me to become completely independent. I am now a developer with 100k+ downloads on SpigotMC and have worked for several large projects. If you are a beginner or intermediate programmer, I would recommend MineAcademy to accelerate your learning. However, some lessons may be longer (over an hour) and you should be prepared to rely on Foundation for the first several months.