(Obituary via The BBC)
I just discovered Banks several years ago on the recommendations of people with similar tastes in SF. His Culture books were hugely influential, especially in the kind of SF that uses post-scarcity settings. If you haven't read anything by him (I still haven't finished all of his Culture books myself) you owe it to yourself to give one of them a go.
His characters were variable, ribald, occasionally brutal, often alien in thinking, but always interesting and layered beings. Notice that I don't say people. The personalities of the drone and ship Minds were at least as strong as any human(oid) or (mostly) biological entity in the Culture.
Most of the Minds also had a strong sense of humor, however oddly it might express itself. Culture Minds name themselves, after some deliberation, with something that they think reflects some essential truth of their being. There had to have been something right with a man who came up with ship names like Falling Outside The Normal Moral Constraints, Frank Exchange of Views, and You'll Clean That Up Before You Leave for various flavors of dedicated warships, among many other names lacking in significant gravitas for more general purpose ships.
From what I've read about the man himself, that humor reflected his personality. He always maintained a sense of wonder, which is probably why the Culture books were so imaginative, and why his darker plots were so very, very disturbing. We've lost one of the greats here, one of the thinkers who shape genres, one of those who could maintain the duality of a childish outlook with an adult's incisive view of the world and combine them to make something truly original.
Like Djan Seriy in Matter, I imagine him having a dialog with the cancer that ends with him saying, "Oh. Go. And. Fuck yourself," and letting go…