Went to see Shutter Island today, I am so disapointed

Maybe it's because I read the book and enjoyed it so much (I read it in a day, well at night... Got to love insomnia) The book blew me away! I expected so much more from Martin Scorsese. The cast was brilliant (Ben Kingsley, Leonardo DiCaprio and Emily Mortimer). Perhaps it's better to read the book AFTER your see the movie.
Anyone else see it? Thought?