I have already praised Dan Simmons in my review of Hyperion. It is clear that he is intelligent and has a knack for blending things together. I wanted to say this to remind the reader that though the majority of my comments are negative, it is only because I had such high expectations after Hyperion.
Hyperion was incredibly original and well-constructed. There is a hint of innovation in the Fall of Hyperion, but this seems primarily a shallow mask for the necessary linearity of the novel. This is basically the conclusion to Hyperion, where Simmons has to explain everything that was introduced in the other book. And if you read Hyperion, you have to read this book, no matter what. I should not be able to convince you otherwise and will not attempt to do so.
I guess what annoyed me most about this book was the amazing complexity. It must have taken a lot of effort to put this together, but you wonder if maybe Simmons added too many layers. Things brushed over in one chapter could be the subject of entire books. Explanations were hasty and fairly uncreative. Typically, an author reveals elements about the universe through the story without flat out telling it to the reader, making the reader become aware of things without him/her knowing that it was the author's intent. However, in Simmons' rush to cram so much information into this one novel, I felt like he was talking to me and not telling a story. Furthermore, it was very strange at some points. You expect a science fiction novel to be weird, but some of the stuff in here was really weird. My advice is to accept it and move on, even if it seems absurd to the point of stupidity.
Overall, I would say that the pace at the beginning is normal, but towards the end is just a blur. Revelations and curveballs come from leftfield to reach the conclusion. Still, the story is solid, and any reader of Hyperion will not be more than mildly disappointed, if disappointed at all.