So I've been on a Bond kick as of late and I just finished re-reading Casino Royale.
1) I enjoy Fleming's terse, masculine prose. He doesn't waste time describing scenery, which has always been a pet peeve of mine (I find long stretches of Lord of the Rings to be agonizing due to Tolkien's love of topography). There are certain modern authors who would be tempted to stretch out Bond's explanation of baccarat until it read like a manual, but Fleming's Bond sticks with the basics.
Fleming's style also tends to gloss over the decided lack of Bond-ian action. The card game is one of the most tense scenes in the entire book. In lesser hands, it simply wouldn't work. But Fleming understands that less is more, and he doesn't stretch things out.
Even when Bond is feeling melancholic or philosophical things move along nicely. There's a poetry to the way Bond debates the existence of good and evil, and Mathis' rebuttal.
And I think "the bitch is dead" is such a beautiful summary of Bond's tragic experience at the end (and one that transferred brilliantly the big screen).
2.) The philosophy. Fleming portrays Bond's struggle with the nature of good and evil brilliantly. His discussion with Mathis is possibly the highlight of the entire book. And it's Mathis, not Bond, who has the best line: "Surround yourself with people, James. They're much easier to fight for than principles."
1) The lack of action. I'll admit my expectations have been shaped by the films coming into the books, but I can't help but feel like there's not as much going on here as there should be. Worse still, Bond often comes across as ineffectual and passive. He doesn't live by his wits so much as contrived plot devices, like when the bombers mistakenly kill themselves or the SMERSH agent doesn't kill Bond because he doesn't have orders. Are we really to believe that SMERSH agents won't kill an MI6 spy on sight?
Fleming basically makes the classic mistake of substituting shock for suspense.
The film improves on this flaw without losing the book's tone. We see Bond killing the double agent and his contact. The terrorists threatening Le Chiffre make for a more exciting scene that bombers being idiots (and being explained after the fact). Quantum's decision to let Bond live is explained by M as Vesper having bargained for his life. And Bond sees Vesper Lynd commit suicide in the most dramatic fashion possible rather than sleeping pills and a note on the bed.
2) Bond isn't as fun here. He's actually a bit of a bore. The movies might have taken things too far sometimes, but it's hard for me to imagine a Bond who doesn't deliver witty one-liners. I'll admit I'm a sucker for corny one-liners (like when a foe dies in a press and Brosnan's Bond says, "They'll print anything these days.") Again, the CR film manages to accomplish this without compromising the tone. (The torture scene comes to mind: "The whole world will know you died scratching my balls.")
All in all I think it's a brilliant first effort, but I'm glad Fleming toned down the philosophy and amped up the action in subsequent outings.