It was okay - not as good as the first two books, but better than most modern SF I've read in the past decade.
Between The Fall of Hyperion and Endymion, the Consul died in mysterious circumstances and his ship returned to Hyperion to be guarded by A Bettik and the poet Martin Silenus. The One Who Teaches was born, and stepped into the Sphinx time tomb to come out nearly 300 years later.
This book begins shortly before she returns from the Sphinx, and is about the android Bettik's and Raul Endymion's attempt to protect Aenea, the One Who Teaches, and their trip through the supposedly deactivated farcasters on the old River Tethys. They are being hunted by the church, who have used the parasitic cruiforms discovered in Hyperion, to achieve resurrection in life, and who have rewritten history to blame the Ousters for the destruction of the former Hegemony (when it was actually elements of the TechnoCore who did that).
The book feels padded. Some phrases are repeated more times than is comfortable (eg "parade rest"). The sense of the future is spoiled by such details as dress - Aenea is described as wearing clothes that sound very 20th Century.
This would probably make a good TV miniseries.