If you've read the book, the movie's storyline is a little disappointing. If you've seen the movie and haven't read the book yet... You really need to. It is most satisfying, and will give you a better understanding and appreciation of the character Creasy.
The location switch from Italy to Mexico works well. Of course, we miss out on the Isle of Gozo. As with most novel-to-cinema adaptions, we miss out on a lot of subplot (Creasy's women). And as is inevitable with a major studio production, the ending has been "Hollywood-ized." (can't tell you more without giving away the ending... read the book).
However, Denzel Washington does an excellent job portraying the character Creasy, as I knew he would. Dakota Fanning is Pinta, no question about it. Christopher Walken, always a good choice, was an excellent casting choice here. A.J. Quinnell would be proud. Marc Anthony...? Well, A.J. Quinnell would understand.