Nostromo is considered a classic (and Conrad's best book) for a reason: it's a great book. But that doesn't mean it's an easy read. It is - unlike so many modern literary books - a book that requires you to actively engage.
As Jean Luc Godard said Every movie has a beginning, a middle, and an end - but not necessarily in that order. Conrad does something similar on the page. Chapters will begin in one year, then shift POV to another character and skip ahead (or back) years. And then dhift again. Characters will be referred to by two or three different names. The first half of the book is a slow set up for the action, which doesn't really kick in until the second half. It's not without flaws. The book (written in 1903-04 during the foundation of the nation of Panama and the US building of the Canal) is as casually racist and xenophobic as was that era. Arguably anti-Semitic. However, it features more female characters than any of Conrad's other books, and the only really honorable ethical person in the book is the woman in the closing scene. It's overly melodramatic at times, though Conrad's complex ever shifting storytelling style mostly disguises this.
But as an exploration of exploitation of "less advanced" lands by the West, as contrasting idealism and cynicism, as exploring how greed and heroism can coexist in the same person, its power is undeniable.
But it's not for everyone. It requires work and attention from the reader. It challenges one. If you are up to the challenge, it's a powerful book.