The first time I'd heard of this book was while watching the movie "Wall Street" (in high school, 1988-89).
The first time I actually read this book, I was in my 3rd year of college (1993-94) - I read it to get better at playing the PC game, "Civilization".
The second time I read it was to brainstorm ideas for a retreat about "spiritual warfare" (1999). I not only eventually wrote up that retreat, but also ended up being the director for the retreat (2000).
This book is deceptively short, reads like a bunch of proverbs, but is profoundly instructive, not just on war (the military examples that are footnotes to various points in this edition are fascinating and excellent for illustrating the point), but also as a philosophy/religious text (the parallels to the orthodox practice of the Catholic faith are almost innumerable!), a business primer, an aid in strategic planning and gaming, and (most shockingly!) a self-help book.
"If you know yourself and you know your enemy, you can survive a thousand battles." That one statement will give you the motivation you need to continue to learn more about who you are - your strengths, your weaknesses, your true desires.
Read it and re-read it - even if you are not into war, or gaming, or business, or anything else I've described above. At some level (or levels), you are sure to appreciate it!