God Emperor of Dune by Frank Herbert

The sheer magnificience of this book astounds even the most intellectual of minds. No it is not a normal book by most conventions, there is no true action to speak of, and this book mainly centers around the dialogue between Leto and those around him. But it is a most important book in that we see what it is to be a messiah and more importantly what it is to be human and how one can never truly be released from that bond.
Leto's struggle is within himself and this is shown through his journals and his anger with humanity. Leto is the ultimate teacher and all of mankind are his students and he sees the patterns mankind holds intrinsically. Each of the characters is well developed with Leto being the one of the greatest of all time.
This is not simply a book by an incredibly intelligent man, but Herbert's warning to mankind about becoming entrapped in one's own patterns and how it takes an outside observer to chnage those patterns.

Three millenias have passed after Leto Atreides II took over the Imperium and started his transformation to Shai-Hulud, the great sandworm. The Empire now enjoys peace but Leto now is a hulk of pre-worm form, retaining only his face and hands as remnants of his lost humanity.  He is now God Emperor, revered by his all-women Fish Speakers troops and people of Arrakis.  The Tleilaxu, Guild Navigators and the Bene Gesserit are all under his grip; his weapon, the spice stock which is now decreasing.  Following the extinction of the sandworms, spice price is rising.  Leto takes the opportunity to control the spice.

   Amidst this grip is the daughter of his majordomo or minister, Siona Ibn Fuad al-Seyefa Atreides, daughter of Moneo.  She hates Leto and has stolen his journal.  The Duncan Idaho ghola, ressurected by the Tleilaxu under Leto's request, allies himself to Siona and plans to destroy the God Emperor.  Leto has foreseen this and prepares himself to marry the Ixian ambassador, Hwi Noree.
   In this novel, the Fremen are no longer the proud warriors of the Muad'Dib past.  They are called the Museum Fremen and lack the blue-on-blue spice saturation.  All they do is perpetuate traditions of their once-powerful warrior ancestors.  All has become a mere puppet of Leto II who posseses memories of humankind's Terranic past. 
   The Tleilaxu, however, allies themselves with Ix and try to assasinate Leto.  But all of their plans are thwarted by Leto's Fish Speaker troops who follow the tradition of the Sardaukar crack troops given to him by his cousin, Farad'n of House Corrino, three millenias before. 
   God Emperor of Dune is vastly different from its prequels.  It is full of philosophy and contrasting realities.  For example, Leto knows that the Duncan Idaho gholas will certainly rebel at him but he keeps ordering the reproduction by the deceptive Tleilaxu.  He never changes from what he was during the time oh his ascension.  He knows that every risk is worth to make his Golden Path's wheel turns after his death. 
   Mr Herbert wrote a brilliant sequel to Children of Dune.  This novel focuses on Leto Atreides II who will shape the future found in "Heretics of Dune".  The Dune sagas are truly hard to put down.