Part of me really wanted to like this novel, after all, I am a big fan of Clarke's work. But I must say, I was somewhat disappointed with the story. After such successes as Rendezvous with Rama and 2001, you would expect the works to only get better, but the results are not up to par.
My first problem with this book is its lack of centrality. There is really no "protagonist" character, unless Loren is counted, and there is very little in the way of plot, complication, or conflict. I'll admit, I was not exactly sure how the entire planetary-travel idea would be fixed, but the solution was presented within the first 100 pages, and the rest of the book was anticlimatic to the nth degree.
Also, Clarke seems to be using this work as merely an excuse to push an anti-family, anti-religion platform, which would be fine if it was that sort of a story, but the ideas don't seem to go with space theater very well. On a related (sort of) note, there is something to be said for conciseness. The chapters dedicated to how this "futuristic" technology was "discovered" or "works" are unnecessary, and detract from the meat of the story.
And, yes, there is some meat to this story, with a good amount of character development. But there is still no conflict, and very little in the way of interesting plot twists. Subplots detract from the main action, and in this case there is little enough of that to go around.
To simplify: what substance is here is an excellent morsel of food for thought. Unfortunately, there is so much fluff around it and nothing to keep the reader's attention after some time. You're better served with one of the 2001's or Rama's than this one.