Robert Charles Wilson's Spin (
which I wrote about a while ago) is a wonderful book, one I recommend regularly; Axis, the follow-up to Spin, is not so wonderful.
Axis is far from a bad book. It is entertaining and includes some well-crafted scenes, some focusing on the characters and some on the scenery of a new world or on the results of the general weirdness that goes on (to say more would be to give away too much, I think). But the philosophical weight and character-driven focus of Spin is missing. It seems at times as if Wilson does attempt to build the same kind of balance between character and plot and to carry out the same forward momentum that Spin maintains so well, but these attempts in Axis feel shallow in comparison.
What's more, while the sequel does elaborate more on the breadth and function of the Hypotheticals than Spin is able to do, this elaboration is only a small part of the novel, a part that is dealt with in short, fast-moving chapters that are chock full of physical and (at least intended) emotional upheaval. This makes for a good adventure story but doesn't allow for much thought beyond, "Oh, so that's what's going on... Okay. I get it, I guess." There is neither time nor room (in the book or in the ideas) for meditation. And that space for meditation is what makes Spin a great book and not just an exciting book.
If you've read Spin and you're just dying to know more about the new worlds that are opened up by that book or about the Hypotheticals, you might want to read Axis. It will provide more information. But don't read Axis expecting another book of Spin's caliber.