I think that a lot of readers were disappointed in this book because it is so different from Dune: rather than achieving power - a far more compelling plot - Paul is wielding it. This latter makes from a much more complex, even mundane, story, for it is about maintining political equilibrium, personal rumination, and the mechanics of fate.
Thus, as a political junkie, I thoroughly enjoyed this book. It is written from the perspective of a profound grasp of human history, in particular from a religious point of view. Paul is seem as a messiah, an oracle who is shaping human destiny. While molding the next phase in the evolution of man, he feels trapped by the necessity of fate. Interestingly, he compares himself to Christ, but also Genghis Khan and Hitler. How many scifi books could ever boast such a scope? Very few. Only Asimov and Octavia Butler come to mind, the absolute top tier of scifi writers.
This is a book for mature readers, not those seeking some swashbuckling shoot-em-uper. Paul's character matures, as humankind is on the brink of enormous change that is only alluded to.
The additions to the Dune unverse are also fascinating. You get the Tleilaxu and their gholas as well as allusions to IX and the suborndinated guild and Bene Geserit. Very fun and complex.
Warmly recomended.