I bought this book having just seen the amazing film Shutter Island (based on a Lehane novel).
I must say I was extremely disappointed. I am not a regular reader of detective fiction, but even so I found the plot to be nothing more than a sequence of Sam Spade clichés strung together, from the hard drinking Irish American detective stereotype to the over reliance on standard genre tropes (characters being shot moments before revealing a secret etc).
The dialogue is glib and comes across as if the characters know they are in a detective novel and have already read the plot outline. The book clearly wants to make a statement about important issues like race relations, domestic abuse and corruption, but has no idea what it actually wants to say on the subject.
Perhaps worst of all the book breaks the literary golden rule and is pretty much all tell and no show. Vast tracts of exposition take the place of any kind of characterisation or development.
My understanding is that his later books are somewhat better. On this evidence I'm not going to take the time to find out.