Well, I got to the end, and was just about to write something about it when I discovered that John Scalzi had already said what I was going to say. Scratch that for an idea.
On the other hand, I can note that Banks seems to have been aware of what he was doing and even advertised it. On page 474, just as the plot is starting to warm up, he has his heroine say, “It’s like all war; months of utter boredom punctuated by moments of sheer terror.” Not that the previous 473 pages are actually boring, they just move much more slowly, and are full of that glorious space opera stuff of, “You think that’s big and impressive? Ha! Wait until you see THIS!”
And the occasional bit of philosophy, of course. I suspect that much of the message of the book is bound up in just one paragraph spoken by the “thing I can’t talk about because it would be a spolier”. That and a few musings on wealth and its uses by the admirable Mr. Holse. All else is entertainment, but it is good entertainment.