I've always found their resources particularly valuable when I really want to go deep on a subject in a way that video courses (my other preferred way to learn) don't seem to always do.

And I think they strike the right balance between academic theory and practice. For example, I'm currently going through their Cyber Security Base https://cybersecuritybase.mooc.fi/descriptions/ and it seems very thorough (i'm not a security or devsecops expert so happy to hear thoughts from those who are)