If you haven't seen the first two, Before Sunrise and Before Sunset, they're definitely worth the time. They take place nine years apart, in real life and in the films, and follow the romance between two people. That's all I'm going to say, because just like this last movie, Before Midnight, they're a breath of fresh air. Each movie is about the dialogue and an honest portrayal of how people might grow as a couple.
Of course I had to watch it with a beautiful bottle of wine, and it made for some lovely intellectual conversation afterward. So definitely make time for these films if you're into genuine slice-of-life work.
If you've seen it, let me know your thoughts. I'd love to continue the conversation.
Happy movie watching.