My Problems with the Movie (Spoiler)
I thought it was a decent, but pretty flawed, movie. As much as I admire Laura Linney and many things she's done, Mark Ruffalo's character was the only compelling one for me in this film. But I had a more fundamental problem:
In a movie with a good script and plot/character development, events/actions may (and usually will) occur that are surprising, but they make sense/are logical in terms of that development. It is a mark of a weak script that things happen that are not only surprising but even upon reflection make no sense in terms of anything that came before. (Grade B and worse movies display this tendency often.) There were several instances of this, most notably when Sammy goes to bed with her boss. Given their relationship/interaction up to that point, this made no sense at all.
A minor, but grating element: Kenneth Lonergan (writer/director) obviously loves Bach's Cello Suites (as I do.) I think that they are some of the greatest pieces of classical music ever written. But using them here may be the worst choice of music for a given movie I've ever heard. Plus they came in LOUD. It's as if the Lonergan wanted to rub the audience's nose in how erudite he was to use that music in this movie.