I really should like Charles Sheffield more than I do. His books are packed full of science fictiony goodness, and -- most importantly -- have that sense of pace that makes them compelling reading. But for whatever reason, Sheffield has always remained one of my second-tier authors, one of the guys whose books I'll buy if they look especially interesting, but not otherwise; and whose books, once purchased, tend to sit on my bookshelves in dusty neglect for a long time.
My suspicion is that the problem comes down to simple numbers. Sheffield's written a lot of books, and it's hard to treat something as precious when it's littering up the landscape. (In a way, P.G. Wodehouse suffers from this same problem: If he'd only written five novels, I'd've read and re-read them each a dozen times; as it is, I don't know if I'll ever even read his whole oeuvre.)
The reason for this introspection is that I picked up Charles Sheffield's Tomorrow and Tomorrow this past weekend, stayed up late reading it compulsively, liked it enormously, and wondered why I so rarely read books by such a good author.
Tomorrow and Tomorrow is a deep future book: The protagonist travels forward into time via a number of artifices (beginning with cryo-freezing in the present day), and gets to spot-check the state of human progress at several points in the increasingly distant future, until he ends up yea verily at the end of the universe itself.
Structurally, this makes for an episodic book. While there is an overarching story, million-year time skips inevitably lead to a certain discontinuity in the supporting characters and setting, and Sheffield uses these discontinuities to turn the story in several very different directions -- different enough that I wouldn't be surprised to learn that this was a fixup novel, combining three novellas and a few short stories (there are a couple of "Interlude" chapters that are nearly capable of standing alone).
The first third of the book can loosely be described as Observing The March Of Progress, as we see human society evolve technologically and culturally for some thousands of years; the second third of the book concerns an intergalactic war; and the final third is about Our Posthuman Future. On the whole, these thematic twists work well. Just about the time we're starting to get a bit bored by seeing human civilization advance, we get our big war; and about the time that we're starting to tip into danger of being a Baen book (and now I'm trying to imagine the process of cover uglification that would be necessary to turn this into a Baen book), we switch to getting some perspective on the universe.
It's interesting, it's fast-paced, and it's got neat ideas (though none of them have that compellingly original feel that you get with, say, Vinge). And I'm still wondering why I don't read more Sheffield than I do.