The central conceit of this novel, the "zones of thought", is brilliant.

The laws of physics change as a factor of distance from the galactic center, allowing increasingly advanced civilizations toward the edge of the galaxy. Earth's civilization, trapped in the "slow zone" - the interior region where nothing travels faster than light - is limited to the solar system by that impassable barrier.

This idea allows sci-fantasy staples like FTL travel and interstellar civilizations to exist within a rigorous sci-fi universe. It also creates a rich analogy between galactic geography and the hierarchy of oceanic life forms. Entities closer to the galactic center are tend to be lower life forms, those closer to the edge are more advanced.

If only the story was as compelling as the setting. Half of the book is a grand space opera about the struggle to contain a godlike extragalactic threat while the other half involves a political squabble among factions of a pre-industrial race in the slow zone. These things are not equivalent in importance, and the planetbound sections of the book are comically tedious.

The sequel seems to narrow the focus - but in the wrong direction: it's set entirely on Planet Pointless. Vernor Vinge has terrific ideas, but he needs to find a better way to use them.