It is still a very original book, and will strongly influence your thoughts on basically everything: love, music, literature, architecture, science, religion.
Volume 1 is also amazingly accessible, and often very funny. If you don't like dry philosophy books which must invent their own language systems, but still fail to bring their basic points across, you will be in good company - because Schopenhauer hates them. He frequently reminds the reader that if someone has truly and fully understood something, he can explain it in simple sentences. And Schopenhauer delivers.
I'm only just starting these two but they've already caused a fundamental change in how I perceive propaganda and how I think about what leads a person to have distorted, clearly false views.
The first thing I've learned is that propaganda is measured. That it operates like a business where outcomes are measured and tests run on smaller populations. That most countries do it, but that the most effective propaganda is selectively highlighting the truth so that the source develops trustworthiness.
The other thing I learned is that propaganda isn't about shifting someones opinion, though that is often a useful middle step, it's about driving specific actions, like getting someone to stay home on voting day or getting someone to join the military.
I'm not advocating that all of us here go and buy the same book. What I'm trying to highlight is that propaganda is now in full force online and we're the ones (web developers, designers, data analysts, machine learning developers, sys admins) that have the most amount of power to augment our technical knowledge to push the world towards a peaceful, more prosperous future by fighting falsehood-riddled propaganda.
Lastly, if you're a reputable angel investor interested in fighting back, I'm working on a stealth startup that I think will make a lot of money and really help the world. My email is in my profile.
 Really, Schopenhauer is probably too cerebral for most and more focused on philosophy and will not on propaganda itself, so I only really recommend the first.
 For obvious reasons.