This is the last of the Hyperion Cantos and I am just going to assume that anyone reading this review has read the previous three novels. If you haven't go and read Hyperion, because it is really very good.
This is the fourth and final book in the series. The strength of the books has never been in the plotting and this book has stronger plot holes than the others. In particular, Simmons revises several established facts and in a book that condemns the whole idea of institutionalized resurrection brings far too many characters back from the dead. Furthermore, as the series has progressed it has become more and more about religion and this book, which revolves around a messiah's preaching is the most religious of all. The reason that is a problem is that while Science Fiction writers often write about religion they often do so very badly. Simmons isn't bad. He has a good knowledge of comparative religion and Roman Catholicism in particular, but he is not tremendously wise about religion. All these faults have gone through the series to some degree after the original Hyperion.
However, the strengths of the series continue. Simmons work is informed by literature, something which is very rare for American Science Fiction writers, so the quality of the prose is very good. Furthermore, his characterization is adequate, which might seem like damning with faint praise, but many Science Fiction writers are abysmal at characterization and Simmons is not. His action scenes are quite good and in its space opera elements it is quite good.
However, there are two things which Simmons has always excelled in in the Hyperion Cantos and they are the creation of The Shrike who is the best monster in literature if you ask me and in the creation of surrealistic landscapes. I don't want to ruin the surrealistic landscapes in this book, but they are just as good as ever and to me, it is a defensible view that the Hyperion Cantos contains the best surrealistic landscapes in all of literature. They are good and clever, endlessly different, vivid and compelling. Hyperion is one of the best Science Fiction books written. The reason to keep reading is those landscapes. The Hyperion Cantos is in many ways like the original Dune Trilogy, which is informed by literature, has surrealistic landscapes, is set in the far future and revolves around religion and a messiah figure. For me, the Hyperion Cantos is superior in every way to its more famous literary cousin. The whole Cantos is well worth reading.