Big fan of Dennis Lehane since I read "Mytic River" a few years before the movie was released. "Shutter Island" was also an intensely captivating heavy plotline conveying some life parables that I found I was residually ruminating on for awhile after finishing the book..
IMO, unless you're talking a straight linear plot line romantic or action type flick, it's almost impossible for movies like these to capture and convey the book's multi-layered complex essence. Viewing them usually ends up disappointing me, although I knew that I might have felt different if never having read the book. ..so I'm gonna withhold my decision on whether or not to see it.