To me, and many fans of the James Bond franchise, to say that the new Bond film will be better than "Casino Royale" is a big claim to make.  After a dissapointing end to the Pierce Brosnan movies with "Die Another Day", and a large gap between Bond movies, "Casino Royale" was a beautiful restart to the Bond series, and a film many consider to be one of the best Bond films ever made.  At first, Daniel Craig's casting as Bond was immensely despised, leading to websites calling for a boycott of the film.  After the film's release, Craig was praised for his portrayal of Bond, taking the character back to how he was in the original novels.  The follow-up, "Quantum of Solace" was an exciting premise, being the first direct sequel in the Bond series.  I thought the movie was terrific, but didn't live up to its predecessor by any stretch of the imagination.  That's something that even Daniel Craig admits to, saying the Writer's Stike was a fatal shot to the production,

"We had the bare bones of a script and then there was the strike and there was nothing we could do. We couldn't employ a writer to finish it. You swear you'll never get involved with sh*t like that, and then it happens!"

To help finish the project, Craig and director Marc Forster wrote several scenes, to which Craig admits,

"And a writer I am not..."

Part of the problem resulting from the lack of a completed script was the making of "Quantum of Solace" into a direct sequel to "Casino Royale", something they never intended to do.  This is part of the reason that the use of the criminal organization "Quantum" is not being used in "Skyfall".  Craig is very open about his lack of personal satisfaction with "Quantum of Solace", saying it is very important to him for the next movie to be even that much better. 

Early into shooting of "Skyfall", Craig is very optimistic about the final product, partly owing to the mutual love for James Bond movies he shares with "Skyfall" director Sam Mendes,

"I really think this one is better even than 'Casino Royale'.  Sam Mendes has lived with Bond all his life, and he grew up with Bond in the same way I did. We have exactly the same reference points, we both like the same Bond movies, and we both like the same bits in the same Bond movies we like. We sat down and we just rabbited for hours about 'Live And Let Die' or 'From Russia With Love', and talked about little scenes that we knew from them. That’s how we started talking about it. That’s what we tried to instill in the script. He’s been working his arse off to tie all these things together so they make sense... in a Bond way!"

via Empire Magazine