I read the most recently published Culture novels The Hydrogen Sonata (2012), Surface Detail (2010) and Matter (2009) as well as a few of the earlier ones like Use of Weapons and Excession. The only one that I thought was truly outstanding was Matter. They tend to be quite long books, with intricate plots the author uses to comment wittily on different aspects of our own (western) culture using (very dark) humor. I also read one of his earlier books, The Algebraist (mainly because the title seemed mathematical).
Banks had apparently announced earlier this year that he had terminal gall bladder cancer but his death a mere two months on June 9 later came as a shock. His final book, The Quarry was published just days later in Europe. It's not another Culture novel, but a semi-biographical book about the final weeks of middle-aged guy dying of cancer. Write what you know, I guess!
Banks passing was noted by several famous British authors like Neil Gaiman, Ian Rankin and fellow scot Irvine Welsh (Trainspotting).