Your response is valid, as I think the suggestion was too aggressive. But I do endorse (what I think is) his main point: understanding how to design systems comes from working on them, not reading about them. So it's better to work on problems than to read about them.

More specific advice depends on what your background is and what you're doing now. (For example, are you a student? A CS student? How much of a CS background to you have? Are you working full-time? If so, does your job involve programming? Do you have time to hack on the side?)

I'm a Systems' Engineering student, almost finished my career. I'm working full time already, and my job involves programming and design as well, but I want to learn more and improve my skills. I have some time to hack on the side, but not so much, since I'm trying to wrap up everything related to my career at the moment.

You mean your career as a student? Have you taken any CS courses? (It's okay if you haven't, it's just an easy way for me to know what you know.) What kind of programming and design do you do at your job?

Yes, sorry. I meant that I'm close to getting my degree, and I'll be a system's engineer (that's what's going to be printed on my diploma). The entire degree is based on CS courses, so yes, I got my share of them.

Although we have two courses on System's design and System's engineering, teachers here are not very good, and I feel I didn't learn almost anything from them. That's why I want to read more about it and really improve my skills there.

At my daily job I work on several short-time projects, using MS technologies. Sometimes I code .NET, do some basic design for an application, but nothing really big. I don't stop and think about scalability, performance, etc. Those things usually come unannounced later when the application starts to fail in some environments. So, you can see, I'd benefit from learning more about System's design.