The first time I read this, I thought of it in terms of how long science fiction and horror will ride the same bus. Of course, that was 20 years ago. Now I see the wheel of fate and I feel so much sorrow for Charlie. On the other hand, I'm satisfied that I've had my whole life to enjoy, rather than a few months of confusion and misunderstanding. The first time I read it I had thought entirely about ST:TNG and how writing has improved since this novel was written. Now, I appreciate it for how undiluted the main force of the story progresses. I can't help but compare it to Alan Glynn's novel "The Dark Fields" or the Limitless movie. In the end, maybe I do prefer my hollywood endings, but I still appreciate and expect the disappointments in all of the stories that make life and art. 
 This is a classic, and I suppose it will always remain in my heart, but no longer as a novel of caution, wish-fulfillment, or an allegory of living and death. It is slightly deeper than that, now.