I'm not going to give a long or exhaustive review. A bazillion others have and the movie was released over a year ago--so my giving any sort of in-depth analysis is just needless repetition.
The movie's biggest strength is the acting. All three leading actors did a fine job and this was necessary to carry a film that has no special effects, explosions or love scenes. The vagueness of the film is also a strength. After all, the film gets you thinking and yet there is definitely no clear-cut answer as to what really occurred in the film. There is lots of room to foster discussions and debate. And, while I am a strongly opinionated person, I wouldn't have changed much of the film at all--except the very, very end when Meryl Streep's character, for the first and only time, shows some doubt and emotion. This just didn't seem true to her character. Still, this is a minor concern--and who am I to say, since I didn't win the Pulitzer Prize (last time I checked)! Some may hate the vagueness and want a very clear explanation as to what, exactly, the Father did--if anything. Some may hate that the film actually isn't vague enough (I slightly tend towards that). But what I love about all this is that so many different people see so many different things--mostly based on their own prior experiences and expectations. I could easily see someone seeing gay issues, pedophilia (and it's talked ABOUT but never even explicitly said) or a thousand other possibilities--or it could simply be a metaphor for McCarthyism. Who knows? And that makes the film so interesting.