Sorry, but I just had a huge urge to dig this thread up.
I saw the film back when it was in theatres, but I just bought the DVD and watched it again tonight, and feel a need to reflect.  I've been a huge bond fan since I was a little boy.  My grandfather really got me into the series.  I've seen all 21 films and even read some of the novels (Ian Flemmings original Casino Royale included).  I want to say that Casino Royale is definitely in my top 3 bond films.
Ever since his debut in Goldeneye, I liked the Brosnan Bond.  And I was pretty disappointed to see him leave.  But when I heard he was being replaced by Daniel Craige I was actually kind of excited and interested.  I've seen Craige's acting before, and thought he was awesome in Layer Cake (which is a tight movie btw, I definitely suggest it).  I know this was definitely against the general concensus.
In my opinion, Craige was amazing.  Definitely different, but non-the-less amazing.  Especially after reading the novel, this was the Bond that Flemming wanted to portray in his debut novel.  The writers were right in pursuing a "darker" take.  This story basically explains why Bond acts the way he does in the every other story.  You have to remember that this bond is new and fresh.  He just killed 2 people for the first time.  And this was the first (and only) time, that James Bond legitimately fell in love.  Yet that was snapped from him in a heartbeat.  And Le Chiffre tried to break him like a horse.
I might be camping out for Bond 22 when it comes out sometime  within the next 2 years.