According to (500) Days of Summer, Henry Miller is attributed with the advice that "the best way to get over a woman is to turn her into literature.” Scott Neustadter updated that sentiment, and with friend/co-screenwriter Michael H. Weber along with obvious influences from Woody Allen's Annie Hall, worked through a previous relationship by creating the year’s best film about love.
Right at the beginning, the film states it's not a love story. Instead, it's about relationships that don’t work out because one person isn’t as invested, an all-too-familiar dilemma for anyone who has spent much time in the dating world. The story is told by jumping back and forth through time over the 500 days greeting-card writer/one-time aspiring architect Tom Hansen (Joseph Gordon-Levitt) was infatuated with Summer Finn (Zooey Deschanel). Summer gets a job as an assistant to Tom's boss and he notices her immediately. He hears she's standoffish, but a connection is soon formed over their mutual interest in The Smiths.
Learning of Tom's interest through drunken co-workers, Summer reveals the feeling is mutual but she makes clear she doesn't want a relationship even though they will do things many people in relationships do, from playful moments in department stores to wild sex in the shower. Tom is a hopeful romantic and Summer doesn't believe in commitment. Along the way, we witness their ups and downs as they travel together for a while down ultimately different paths.
Director Marc Webb, who makes a great debut as a feature-film director, excels at conveying Tom's mood. When in a state of utter bliss, Tom becomes part of a musical dance number set to Hall & Oates’ “You Make My Dreams.” The joy is completely infectious and much in the same way Tom forgets what Summer tells him, it's easy for the viewer to get swept up and forget the warning from the film's beginning: "this is not a love story." Webb uses a split-screen for a sequence to show the difference between Tom's expectations and the reality of the scenes, and has Tom drift into the foreign films he watches to drown his sorrows.
Gordon-Levitt and Deschanel deliver great performances and play off each very well. His character is extroverted, wears his emotions on his sleeve. Hers is the opposite, and because she gives so little, it's understandable that he couldn't see when she had already withdrawn from the situation.