Joseph Conrad's most famous work is of course "Heart of Darkness," but fans and scholars generally consider Nostromo his masterpiece. One can certainly make a great case for it, as it expands many of the better-known short works strengths to novelistic scale. Like them, it is on the most obvious level an epic adventure and can be enjoyed for this alone. However, again like them and far more importantly, it is deeply symbolic, and its grand display of Conrad's bleakly tragic vision has much to say about human nature, existence, and a range of other topics. That said, it would be selling Conrad's genius rather short to simply say the book adapts his short work to a larger scale. It in fact shows his remarkable diversity, largely forsaking the sea-centered stories that dominated his early work for an intricately detailed and realistically presented fictional world. The novel also furthers Conrad's ongoing technical innovations, making it an important and influential example of very early Modernism. Finally, as always with Conrad, the prose is mesmerizing. This is quite simply Conrad's grandest and very possibly his greatest creation - one of the twentieth century's best novels and essential for anyone who likes his other work.
The adventure aspect is certainly obvious, and greater length lets Conrad work in even more than usual. There is plenty to grab even casual readers' interest: revolutions with numerous battles, political crises, several love stories, family drama, business conflicts, suicide, intercontinental capitalistic and political scheming - even buried treasure. The complex, sweeping story has numerous exciting subplots that eventually come together in a stunning conclusion, making the book seem longer than it is in the best possible way. Nostromo has a sweeping, epic feel not really present elsewhere in Conrad and is in this sense among others a tremendous accomplishment. Conrad is known as a hard writer to get into, but these factors certainly bring wide appeal.
Far more important of course is the overall fictional panorama, specifically the deftly drawn setting. Conrad is often unfairly pigeonholed as a "sea" and/or "adventure" writer, but his fictional Latin American country of Costaguana is one of literature's most painstakingly and believably depicted fictional locations. He knows just what to convey about everything from landscape to speech and goes to great pains to establish a suitable background: historical, social, political, etc. This is greatly helped by many real details worked in from his world travel and voluminous reading. The country seems truly real in a way fictional locales rarely are; we become deeply engrossed in the country and everything concerning it, leading to great suspense and emotional pull. This is indeed so well done that Nostromo seems like a historical novel in the best sense without being historical - a truly notable accomplishment.
Similarly, this certainly has Conrad's most vividly drawn character cast. The characters are truly diverse: young and old, rich and poor, male and female, etc. Conrad clearly had great knowledge of humanity in nearly all aspects - including much first-hand experience - and used it for the good of his work. The characters are shown from multiple angles, creating complex and very lifelike inner and outer portraits; Conrad is well known for psychological insight, and this has some of his best examples. No characters are exalted, though Nostromo first seems to be; they are fully and frailly human with hidden and often selfish motives that are sometimes contradictory, as people's can be. Some novelists try to make characters consistent in order to seem conventionally real, but Conrad knows better; humans are rarely rational or noble, and he rarely shows them as such. Few characters here are conventionally likable, and several are downright despicable, though not always in straight-forward ways. Conrad's depictions are nuanced and subtle, at once artistic and realistic. Several characters are absolutely unforgettable - not least of course the in many ways admirable but tragically flawed Nostromo -, and characterization generally is one of the book's great strengths. This is another area where the novel stands above other Conrad, much less his standard reputation; characterization is not considered his forte, but this shows him on par with true masters in that important regard.
The good character dearth brings up another key point - the dark vision. Few writers - nay, few human beings - have been as thoroughly pessimistic as Conrad, and his works are generally bleak, but this blackness is truly remarkable. There is enough lying, hypocrisy, false motives, backstabbing, and other disgusting actions to convert many to misanthropy. In a large sense the plot essentially dramatizes these unenviable traits as distributed throughout various characters in conflict with each other. Conrad at times seems on the verge of allowing some kind of hope, as when the mine is saved, the revolution is successful, etc. Perhaps more notably, Nostromo for a long time seems the kind of truly heroic character that prior works indicated Conrad would never write. However, it soon becomes clear that he is at least as base, vain, and selfish as anyone but far better at hiding it - indeed, at shamelessly promoting a contrary image. This arguably makes him perhaps the most loathsome of all, yet there is no denying his greatness in many respects. His tragic end in many ways epitomizes poetic justice, yet he is arguably more sinned against than sinning; he is a truly tragic hero, and his immense downfall moves us whatever we think of him.
The novel also notably continues the narrative experiments Conrad began in earnest with Lord Jim. It uses third-person narration instead of the first-person layers he had used to great effect yet is even more complex. The narrative is far from linear, told in a series of non-chronological flashbacks from various points of view that first seem unrelated but eventually coalesce into a profoundly meaningful whole that is a true artistic feat. This technique, along with the intense psychological focus, was extremely influential, but Modernist writers arguably took it too far; one would have to look very hard indeed for an equal achievement. Of course, as with much of Conrad - and as with later writers to a far greater extent -, this is not easy reading. Nostromo is notoriously hard for casuals, but I advise anyone having difficulty to stick with the book; it all makes sense in the end and is worth any struggle. The method will make many want to read the whole over again, and the book indeed rewards rereading as few do. For instance, much can be gleaned by reading the story chronologically rather than as printed. Nostromo's greatness thus stretches almost to perpetuity.
Finally, as always with Conrad, the incredible prose is a major attraction. That English was not his native language is simply incredible; he is nothing less than one of the language's top stylists. His description is strong and his display of various psychological states near-unequaled. Conrad's vocabulary is impressively extensive - especially for a non-native - and sometimes eccentric, but he has an amazing knack for selecting just the right word to convey whatever thought or feeling he has in mind. He is perhaps at his best with tropes, which truly says much; his figurative language is simply unforgettable, and he handles symbolism as only the greatest writers can. Vivid and memorable, his prose kindles a spark in the mind that will not soon die out.
All told, Nostromo is essential to Conrad fans and anyone who appreciates grandly tragic literature and sweeping prose. Those who have read little or no Conrad should begin with the more accessible and shorter early works or a less all-encompassing novel like The Secret Agent, but those who make it here are in for a true masterwork.