[mettamage]

I have a mixed experience. Let's just say that I learned how to work with VUSec security classes when we were replicating rowhammer attacks. Practical? No, but it did give me an intuition for finding very difficult SQL vulnerabilities and completely pnwing my employer (with their consent). So that was really useful.

The fact that I did a course in distributed multimedia systems wasn't useful.

IMO a master CS degree is much better if you already have a few years of experience and have a feel for what you want to learn now.