Writer/director Richard Linklater is a doughy-faced, unassuming man who speaks about his work like he's talking with a neighbour. But what he says is oddly mesmerizing. Similarly, Before Sunrise is purely a dialogue between a juvenile American man, and a dreamy French woman. What they say isn't special, but is oddly remarkable.
Jesse (Ethan Hawke) is an unambitious, pretentious cynic. Celine (Julie Delpy) is the worldly, fearful optimist. Their qualities are the opposing skins men and women wear, but their hearts share the same hopeless romantic beat. They meet on a train, start talking, and decide to stop in Vienna and talk until Jesse's plane leaves at sunrise. They stroll around the city and discuss what they encounter and their innermost theories about the world.
What is most interesting about this dialogue is its unique freedom. Couples gradually build honesty over time. Jesse and Celine are not a couple, nor are they dating. They are somewhat removed from traditional roles because they are free to leave each other at any time. Their conversations are affectionate, flattering, and honest. The loveliest of these is the scene where they role-play talking to their friend on the phone. They're really just talking to each other, but the pretense allows them to reveal their feelings more intimately.
If you saw Linklater's later film, Waking Life, you'd see where this style of analytical/hypothetical dialogue was going. It's not for everyone. Before Sunrise offers no answers, and simply explores the ideas, fears, and dreams of a young man and woman.