I actually read this almost immediately after “Ed”, and it makes for a heck of contrast. Where “Ed” is mostly pretty light and quick, this is all kinds of convoluted in terms of what’s going on with the plot. But it also does that thing that Hughes does really well—it spans a massive amount of time and space, and covers a staggering amount of ground.
The basic concept is truly excellent, though: what if, every time you tried some Cool Science Fiction Thing, it worked—once. And then never again.
It’s a really interesting constraint for a work of science fiction, as well: how can you do enough Cool Science Fiction Things for a full book, when the core concept is that those concepts are consumable? It makes for, as I said, a sprawling world that must be built out—larger than “Ed” or “Ra” had to be, and bringing in some definite “higher-dimensional beings would look a lot like Cthulhu, wouldn’t they?” energy.
The end result is, I can’t recommend this as readily as I did “Ed”, because it’s boggling at times. But it’s a great payoff, and ties together things you wouldn’t at all expect, much better than you’d expect. If that sounds good to you, give it a read.