I will probably get a lot of hate for this, but Dune is NOT a well written book by modern Sci-fi standards (fiction 101 plot, pacing, narrative stuff...).
There are examples of all of the following items in the book, which would prevent any modern fiction from being considered good, let alone amazing.
1. Illogical character motivations/actions, which occur only to artificially carry the plot forward
2. Many overpowered/completely un-relateable characters
3. Uneven pacing, especially during dramatic/action sequences (making some sections downright boring or ridiculous to read)
4. Overlong philosophical exposition, often pretentious in nature
5. Lack of tension as heroes are rarely under real threat
Defenders of the book say that Dune is a book of ideas, not plot. Some also warn to not expect hero/anti-hero tropes. However, if I wanted a story of ideas that "subvert expectation" I'd almost rather watch Disney Star Wars (yes, parts of Dune are that bad once you get over hype, in the same way the recent Star Wars films were bad, but hyped).
As alternatives to Dune: for classic (50+ year-old) sci-fi, I recommend Asimov's Foundation novels. For a slightly more modern sci-fi with fantasy elements, I recommend the Hyperion Cantos series by Dan Simmons. Like Dune, these works also deal with of the direction of human society as it pertains to futuristic government, religion, and technology, but are executed far better than Dune.
In my mind, the book is living off its hype and impact on the sci-fi genre. It is getting a second wind from the upcoming 2020/21 movie. Some of the ideas are great (the spice, the feudal balance of power), but the story is poorly written.
Overall, would NOT recommend...try for yourself at your own risk.