To paraphrase a line from the Simpsons, I'm not prone to hyperbole, but Casino Royale may be the best Bond movie ever. I have been a lifelong James Bond fan, and I don't take the previous statement lightly.
Of course, 'best' is indictive of opinion, not fact. Once you take 'Goldfinger' out of the equation, any fan's top-five list of Bond films will never match another's. Do you like your action, your gadgetry, busty women, your quips to be oh-so snarky? There are far too many traditional elements, almost cliched today (and certainly parodied), that define a Bond film and divide the fan base. Make no mistake, this is the most unique Bond film of all time. That is no opinion, that is fact. It's almost an un-Bond film, it's so visibly different from the rest. This Bond character is a rookie. He makes mistakes. He bleeds (often). He trusts the wrong people. For Christ's sake, he only sleeps with one woman, and only after he has fallen in love! What in the hell has happened to our hero?
Humanity. Realism. Drama. Poignancy. All these things have happened, and it has breathed new life into a series that was beginning (heck, it was well on its way) to become its own parody, making the Austin Powers series seem redundant.
This could only have been possible with Daniel Craig. One movie in and he fucking owns the role. He is the un-Bond. Feral, feeling, emotional, powerful, cold, human. Everything Ian Fleming envisioned when he created the first novel.
The moment that I really felt a sense of awe and downright giddyness was early on in the film, when Bond is chasing a terrorist in Madagascar. After a thrilling run through a construction site, the terrorist takes refuge at his embassy, seemingly escaping. Barely hesitating, Bond brazenly busts into the embassy and yanks his man from their sanctuary. I could barely believe the audacity of this man I thought I knew so well.
The peerless action sequences are balanced with some of the finest acting and dialogue in the series. It should go without saying the Judy Dench is remarkable, but the scenes between her and Bond carry a new relationship. She is tolerant of her new agent, she cares for him, believes in his talents, but is patiently trying to teach him some lessons (which he learns all too well). Craig is bold, cheeky, and confident, even when we know he's wrong. And when he's wrong, like in the aforementioned embassy incident, or breaking into M's loft or stealing her passcodes, M is so baffled and impressed that it tempers her anger. How can she crack down on this man, when nobody does it better?
The movie also doesn't work without a strong performance from Eva Green as the Bond girl, Vesper Lynd. Their introductory conversation on the train to Montenegro is my favorite exchange in the film, and I'm hard pressed to think of better repartee in all the series. Vesper is witty, confident, yet fragile and very feminine, and it's easy to understand how he falls for her. As Mathis asks, "How's our girl? Melted your cold heart yet?" Their relationship is lovely and tragic and essential to understanding what makes this man tick. (Not to always bring it back to Star Wars, but...) It's like watching the prequels and knowing now who is behind the mask of Vader and how he came to be. You aren't able to look at the rest of the series quite the same way again.
Where does it rank amongst the Bond catalogue? If I haven't been plain enough, I'm not sure that question even applies for this film. What I can assure you is that the experience of this film is unlike any other I've ever felt, and I'm going back for another pass soon.
Update: At Commander Bond.net the reviewer compares the love story to that of Casablanca.