Casino Royale took Bourne’s blueprint and used it to rebuild Bond for a modern audience.
I believe this was because of the effect of the Bourne films and they way they depicted secret agents and fight scenes.
The film was also totally different from previous Bond films, which had gone beyond Hollywood and were entering B movie territory. The bad guy is well rounded as his aims are achievable and when he is threatened by the warlords you can see how it affects him. The action sequences get better each time from the opening fight to the construction site to the airport. Sets up both their personalities and the idea behind the poker game. The first time he meets Vesper on the train and the dialogue is just perfect. The opening black and white shots interspersed with the bathroom fight showing is so much at once: Bond’s intelligence to disable the gun in the office, Bond as a physically powerful brawler, Bond as a cold-hearted killer to earn his 00 status. It’s definitely top 3 Bond movies of all time and my personal number 1. I personally was absolutely floored by the film. Remember back when they cast Daniel Craig and people were saying they would boycott the film? I actually think that helped the film overall because viewers went in with low expectations.