I have watched all 21 Bond movies made so far. Casino Royale is not the worst-made of the series, just the most offensive one. The only other time the Bond franchise attempted a complete departure from the established Bond formula the result was the complete flop of License To Kill, which led to a change of direction and the fantastic Goldeneye. But unfortunately this time the experiment was a success, so I'm afraid of what will follow. Both License To Kill and Casino Royale have been praised as "a return to the Fleming spirit", when in truth they are nothing more than shameless attempts to cash in on popular fads of their time: the Bronson / Arnold / Stallone action films of the 80s in the case of License, the Bourne / Transporter films in the case of Casino. Daniel Craig is not a bad actor, but he is no doubt the worst Bond impersonator so far, his lack of class and charisma is almost astonishing. Of course his "do I look like a give a damn" line and his fighting prowess will wow 15-year-olds, but those who remember Connery, Moore, Dalton (in The Living Daylights), Brosnan, even that weirdo Lazenby, may feel like crying at what has become of their beloved icon. Of course you could ask the producers why this supposedly first mission of 007 is set in 2006 and if that means they have dared to completely write off 44 years and 20 films that allowed them to make this one, but their response will probably be "Do we look like we give a damn?".
If Casino Royale didn't pretend to be a part of the Bond series, I would give it 6 out of 10, but it does, so it's a 2.