This book is not without its flaws but it is a miraculous undertaking. I wouldn't call what it tries a very "standard" narrative; that is to say, while it does follow Paul Atreides and there are characters, the main character is almost the world itself and how the reader unspools it over the course of reading it. The only reason we follow Paul is that we are watching a relatively unimportant figure pass from obscurity into myth and legend, whether he wants to or not. The rest of the characters are almost supplements and fulfill roles rather than act as characters with agency--not that Paul himself is one with any higher agency, for that matter, but there is an overall air of fate and predestination and omen throughout it. The mythologizing of Paul is supplemented with every chapter beginning with some quote from an in-universe text that has long since apparently deified Paul, and it becomes stressful when Paul begins to actively try opposing it and you as a reader know that he is destined to become a legend.

Now there are flaws:
1. I don't like how overly sentient the characters are. With the exception of one character getting drunk, everyone knows everyone else's intent in conversation, and what they mean by a certain gesture, etc. This gets worse in the writing: In A Song of Ice and Fire, for example, chapters are written by changing points of view frequently, so we get only a specific character's observations on what has happened. In Dune, the organization is similar, but we'll shift very suddenly from, say, Paul's internal monologue to a very sudden cross-section of Jessica's or Leto's understanding of the situation in the same paragraph. However, this might just be my taste.
2. It is a bit of a grind to read. For one, if you're looking for any humor or you need jokes to cut the tension, this is not the book for you. For perspective, there is literally only one time the characters laugh, but honestly the only time you will be laughing is maybe at some irony at how something was phrased. This didn't bother me, but for all the reasons Dune is great: this uncharacteristic development of a hero over time while still seeming so inhumanly detached and aloof--it is also difficult to read. It is literally unlike anything I have ever read, and so reading it kinda required me to re-wire my brain at times to follow it.
3. Glossary or not, many times you're peppered with a lot of jargon. Most times it is possible to understand from context, but at certain times you simply allow the Fremen and Imperial slang to just wash past you to simply move on.

Now these are flaws that I think are just a matter of my taste and kept me from being so hooked that I finished the book in a night, and it takes it from a perfect five to a four. I think everyone should read this book regardless, and these gripes are more of a warning prior to going in to the actual text rather than it being something to scare people off. Incredible, and I'm so glad I got a boxed set so I can move right into the next one.