A rather less interesting but perhaps more accurate title for this book would be "Qualitative analysis of simple differential equations with practical examples". Put bluntly, this is a boring book.
Examples are things like thermostats, and fish stocks, and capital growth, and epidemics. Things you can model as differential equations. However, this book is about the qualitative analysis of such equations - the modes the system can fall into. It never actually says it, but it's aiming to be approximately right, rather than precisely wrong.
It is, basically, quite boring. Perhaps reasonably worthy. I don't know why it's so boring - it's not a long book, but maybe it's pretty slow despite that. It does have some good insights, but it makes them seem... boring.
For example, in many dynamic systems, we directly attack one variable, rather than try to adjust the system to produce the result we want. To give a topical example, Donald Trump is not actually the problem, he is the result of a system that enabled him to get where he is, and the problem needs to be attacked at a lower level, ideally at a place with higher leverage.
By taking such a structured, academic approach to Systems, you really do end up with a primer on the subject of systems. However, it's neither as amusing, nor as fundamentally insightful as the insanity that is Systemantics (aka The Systems Bible).