My five star rating categories:

Potential (for re-reading): 100%
1. Very high. If a third Dune movie is to be made, I will be rereading this entry again before viewing it. Furthermore, this is my third time reading this novel--extremely rare for me. Even if a third movie isn't made, I will definitely find time for this guy at some point again in the future.
Protagonists (ratio of believable to unbelievable characters): 25%
1. This book suffers from mild Gary Stu syndrome in that the protagonist himself is believable given our privileged readers-eyes-only insights into his psychology, but the actions (and the reasons for them) of the characters around him are verging on the absurd as Paul (consciously or otherwise) uses his Reality Distortion Field to get his way.
Plot (how well-structured/compelling it is): 50%
1. This is a tough category to grade for this novel. From one perspective, this is a novel of epically plotted proportions, highly ambitious in scope and detail and actually follows through on its foreshadowing... mostly. The very ending of the book is one of the most infuriating ways I've ever seen a "classic" novel end--basically, "find out what happens next in volume 2". I have never read volume 2 and am (in the near term) unlikely to given that online reviews of it suggest a twelve year time jump from the end of this book to the next one.
Premise (interestingness of the overall concept of the text): 75%
1. It's difficult to list how many different concepts are introduced to the "beginner" SF reader in this text, and it would have been especially novel to audiences upon first publication. That said, upon finding out that a great deal of its political intrigue and background are loosely thefted from a 1960 fictional account of the USSR's military adventures in the middle east, I am less inclined to give this category full points for originality.
Prose (how smoothly the prose flows/how vivid the description is/how clear the dialogue is): 50%
1. There are portions of the text that are extremely enjoyable to read. There are other portions that could have used an editor. There are whole chapters that jump around inside multiple peoples' heads without a whole lot of rationale for such telling instead of showing. Still, there are no obvious "yikes" moments re: grammar or linguistic logic, so it has that going for it. Very quotable, but also large portions that are simply... prosaic.

Overall:

I recommend this book to people who want to understand what on Earth science fiction is all about (after you've read the Foundation series, of course). Every subsequent entry in the genre, textual or otherwise, has a trace of the spice running in its blood.
I do not recommend this book to anyone who hates the Gary Stu trope/protagonists with an unbelievably massive case of "main character syndrome". This guy can do anything and everything, largely because the story is more interesting if he can than if he can't. Don't expect realistic character arcs here.
I 50/50 recommend this book to anyone who likes the Star Wars franchise and wants to read a novel and not a novelization related to the films. Lucas clearly stole the premise for New Hope from Dune, but don't assume the plots will necessarily be very similar. You may enjoy finding what is similar and what is different here, you mind it irritating to notice that everything is just a little off from what you'd expect after a lifetime of ingesting """content""" from a galaxy far, far away. The question is, are you Padme with her fond memories of lying on the beach, or are you Anakin with his hatred of sand? It may come down to something that petty. Dune has been called many things, but one thing it is not is "universally beloved."

A review by ophiuchus Dune by Frank Herbert

My five star rating categories:

Overall:

A review by ophiuchus
Dune by Frank Herbert