The Algebraist   by Iain M. Banks

It is a big book. Banks enjoys his writing. Starts out being in essence a quest for the holy grail. The final reveal is brilliant. Always hinted at through the book, but never anticipated. I can't get enough of it. Superb. Two races, fast and slow. Main innovation. Rock-hard science fiction, not a hint of fantasy.

I was never able to really visualize the slow-life: twin discs connected by an axle, with arms around the perimeters and that rolled around. Some very strong characters, but Lucas-like (Archimandrite Luseferous with long blond hair - can't help thinking of Lucius Malfoy character in the Harry Potter films).