Having read the book, it's a better-than-average thriller, and the plot is certainly one that begs to be told visually. But every scene from the trailer is DIRECTLY from the book (though they seem to have simplified the codes aspect of the book). Anyone could adapt the book into a screenplay, and anyone with a semester of film school could direct it. Why this story attracted Scorcese will be a greater mystery than the ending.

Shutter Island
Trailer
(2:30)

Shutter Island
Trailer
(2:30)