I think you could say that most of the characters other than Casey Affleck and his nephew were pretty one-note, not just the women, but there was a good reason for that. The whole thing was about Lee and his perspective and the awful feeling that he was carrying around, evidenced by the showing of so much of the action in Lee's flashbacks. The only scenes he wasn't in were those with Patrick alone or with one of his girlfriends, and so there wasn't really room for the development of other characters that much. I don't think there needed to be, though.
And I thought MW was great in the buggy scene because it was long and ugly and uncomfortable, as it would be in real life. The scene where Lee is dreaming about his wee girls and the smoke alarm wakes him up - that was brutal. It must have been gruelling to play that role.
And I am such a sucker for a Massachusetts accent, the way they say 'cah' for car and 'Stah Trek' 
A bad fake Mass accent is so obvious (like some actors in The Departed) but nobody's felt forced in this.