While Giamatti is the primary performer, he certainly does not outperform the other actors. Haden Church's character Jack is not as likable or sympathetic as Giamatti's, which is perfect for Haden Church to nail what it is like to act almost exclusively on instinct. Jack as a character, and his relationship with Miles, seem quite distant to the audience, up until one scene where Haden Church, inevitably reveals how helpless he is to his instinctual habits and begs Miles for a steer in the right direction. His 180-degree turn is still rooted in instinct and an objectively unsympathetic cause, however, which means the scene is much funnier than how I am explaining it now. Virginia Madsen has unmatched passion for everything that she says and hears. Relating to Miles on varying levels of depth, I can understand why he might be so strongly attracted to Mia. Madsen is always listening, no matter how blinded she might be by other emotions. This separates her noticeably far from all of the other main characters, especially Stephanie. What Sandra Oh might lack in passion (mind you, with full intention), she makes up for in how much fun she has in every scene. Even when Oh is ruthlessly furious, I see the fun that she is having in bashing someone with a motorcycle helmet. To all four actors, a phenomenal job, truly.
Payne understands life. He is mature enough to recognize that life forces one to move forward, no matter how much we want to dwell on the past. Ultimately, there is no hope or despair. There is only progress. He draws a parallel to his own craft through Miles' novel, pending publishment, AND the finale of the movie. Still... *SPOILERS* I wish that he had cut the last five or so minutes of the movie. My Hollywood-raised heart had wanted Miles and Mia to get together, but after the wedding and the special occasion to which Miles opened his ancient wine, that would have been enough to explain the growth of Miles' character. The ambiguity of the ending, as it is, is nevertheless welcomed. Nothing felt forced. Really, I feel bad for calling out the ending as out of line, for it worked anyway. It's just that the story is more about personal growth than it is about the growth of relationships, and what happens between Miles and Mia is not relevant. Look, don't mind that. I really love this movie. I love how it skewers the BS of wine-tasting through humour so subtle that outside research revealed a shadowy satirical side to Sideways. I love how scenes jump from one to the next, some with smooth sound transitions and others with sharp interruptions. And I love, love, LOVE the cast. A near-perfect comedy, at the least.