The hype and speculation surrounding the release proves that you can take some liberties provide you stay true to the essence of the material. There was nothing that Casino Royale detracted from the previous Bond films it simply brought it into the 21st century where a majority are saying it's the best Bond film made. The main villain and theme song may not be that memorable but Eva Green is my favourite Bond girl!
It captures - or perhaps recaptures - the vicious streak inherent in the novels but rather lacks their cocktail hour elan, instead trading on modern day par-of-the-course slam dunk action for sensation. It’s not worth debating too greatly what is milked each time from this particular cash cow, except to say the film delivers a much needed kick up the britches to the series albeit a few kicks too many elsewhere.
The pre/post-title action scenes, some scenes with Dench/Green, the unusual Bond torture scene, and the last 1/2 hour hold up the rest, keeping the typical heavy plot interesting. Casino Royale could've been vastly more emotional if its final third was expanded and deepened, or it would've been a tense and thrilling action/spy film with momentum.... if its 1st two acts were cut by 35 minutes.
I used to think this was about as good as a Bond gets, on rewatch I'm not so sure. It's self-serious, dry and looks bad, which is the gift of having Deakins contribute to this series later. Not especially well-crafted or gripping, though the initial chase sequence does the job. I would argue history has proven this was a misguided mood for the series to pursue.