A woman's take on this is probably not the same as a man's. Initially I was put off by Charles Hayden's Church's character crudeness and Giamatti's character's repulsiveness but that changed was I was able to look below the surface. By the end of the movie, I felt very sorry for Church as he was not only dumb and shallow, he was actually so empty that whatever female was before him became a mirror of his need to connect with anything that felt like caring. Church did a fabulous job and was incredibly believable as a has-been wannabe, desperate to hold on to his dream of the kind of good life that is bought by charm and good looks. He is just on the edge or realizing his time is running out and that is a whole lot for this character to absorb as he has never given much to the concept of "thought."
Giammeti is a pitiful, self-absorbed, destructive, depressed alcoholic whose in possession of two "things." He knows a great deal about wine and he has written a book. Nothing else informs him. Yet his performance is so nuanced that we are able to fill in his depth of character and decency primarily through his huge, limpid eyes. What a performance. He should have been nominated for an academy award. This is a role that comes along once-in-a-lifetime for this type of character actor, like Liza in Cabaret.
The women are really nothing more than backdrops or props for the men to expose themselves. Madsen is lovely but you do wonder what on earth she really sees in this man. While he may be redeemable, he is really pretty much a self-absorbed jerk. It is most interesting that this film has been released at the same time as Closer, as they are similar in their exploration of self-absorption. Though Closer explores how destructive its characters are to each other, in the end, Closer is not as intimate and seems more artificial than the sweetly revealing Sideways.