It's been over a year since Iain M. Banks tragically passed away from cancer, and a little over a week until the start of the World Science Fiction Convention at which he was going to be a guest of honour. He had great success writing literary and genre fiction, but it's hard to deny that The Culture, his anarchist, post-scarcity space Utopia, is his most lasting and famous creation.
Certainly on the face of it, The Culture does seem like just about the best society one could hope to live in, hence the expression "it's more fun in the Culture." Its people are wildly hedonistic - everyone is born with glands in their body which can produce practically any drug they want. They're functionally immortal, with enormous lifespans and the ability to upload their personality to a computer and grow a new body for it if they do die. They can go anywhere and do anything they want, and will never go poor or hungry. Being an anarchic society, there are no laws, but because everything is available to anyone who wants it, there's no reason to steal or kill.
What makes all this possible is the Culture's fabulously advanced technology, the pinnacle of which is the Minds. The Minds are the artificial intelligences (though they don't like the term) which run the society, incalculably more intelligent and knowledgeable than even the smartest human, and with very few exceptions completely benevolent. It's a point of contention with many of the galaxy's other races that the Culture's machines, not its people, are what define that society, and it's not hard to see why.
Particularly in the later novels of the series, Minds often feature as main characters, occasionally even protagonists, and they're often more entertaining to read about than the people. This is partly because they're surprisingly whimsical for super-advanced god-machines, and tend to give the ships they effectively are slightly silly names. Unfortunate Conflict Of Evidence, Congenital Optimist, All Through With This Niceness And Negotiation Stuff. Another reason some of the galaxy's other civilisations don't like the Culture is because they don't take their spaceships seriously enough.
Banks has neatly encompassed both aspects of Utopia with the Culture: yes, it would be an amazing place to live, but it's also completely impossible for us to accomplish. The Culture is only as happy as it is because it's a post-scarcity society where the people don't actually have to do anything unless they want to. Fortunately, however, it's not just a civilisation-sized Mary Sue, and there is a much darker side to the Culture which gets explored throughout the series of novels.
Because no one wants for anything, no one has to do anything, and all the heavy lifting is done by the Minds, the Culture's actual people run the risk of becoming irrelevant, and as mentioned before, several of the novels do deal with this problem. When the spaceship you're in can read a dozen novels the length of War and Peace in the time it takes you to blink, and also completely obliterate an enemy armada at the same time, what is there for its human crew to actually do?
This need to interfere with other societies is presented as something of a weakness of the Culture: they believe their society to be the best in the galaxy, and think everyone else should be as much like them as possible. Because of the easiness of life in the Culture, meddling with other people is one of their main ways of defining themselves, and it's hard to think of that as a good thing. Particularly when Special Circumstances starts setting itself arbitrary challenges when interfering with other civilisations, things have a tendency to go wrong: in one case they accidentally caused a caste war which killed billions of people.
Banks did manage to create a plausible Utopia in the Culture, and created one of the most enduring and memorable Science Fiction settings of recent memory in the process, but to say The Culture is perfect is to ignore the care with which he constructed it. No society is perfect, not even one which is specifically intended to be a Utopia, and that's what makes it interesting to read about. The Culture's need to get involved with other people's problems is a bad habit, but without it we wouldn't have any good stories about it.
It's a fascinating balance between the needs of a Utopia and the needs of fiction, and the two combine to make a far more thoughtful take on the "perfect" society than we often get in Science Fiction.