What is the author's style in Endymion by Dan Simmons?

Simmons writes Endymion as a memoir, in which, the main character Raul is writing as he awaits his death in prison. When the story is in Raul's perspective, the narrator shifts to the older and future Raul who is remembering the events in the main story. Then after some retrospect and commenting on his feelings of the current passages, the perspective is shifted back to the younger Raul in the current action. These shifts are unexpected and jarring. Each time this happens, the reader is pulled from the story and it is an effort to reengage.