It's definitely a page-turner, there's a lot of sordid stuff to suck you in, but it peaked around the midpoint and then the ending sort of petered out (the action of the ending, I felt, being sort of a cop-out). In many ways it's a fascinating study of how one powerful person can stealthily control a bunch of weaker people, but it never quite overcomes the inherent coldness of a study -- even though I suppose I did care about some of the characters. (Can a story ever be truly satisfying when the characters you care about most will always be fundamentally powerless?)
It's a good depiction of a middle-class outsider's relationship to old-money privilege, and it's very New England. I especially enjoyed the fantasy-fodder of weekends spent at one of the character's Gothic ancestral mansion. Worth reading, since it's a quickie.