Alternative Character Interpretation: Nearly every problem that led to the breakup can be traced squarely back to Jamie, while nearly all attempts to save the marriage are on Cathy's part.
The very conceit of the musical deliberately invokes this, as both Jamie and Cathy each get to tell their side of the story, and each characters' actions are cast in a different light depending on who's doing the telling.
Crowning Moment of Awesome: "The Schmuel Song", a seven-minute, complete short story told through song, in which Jamie simultaneously proves his writing chops, his support of Cathy's dreams and his love for her.
Crowning Moment of Funny: "Shiksa Goddess" and "A Miracle Would Happen" for Jamie; "A Summer in Ohio" and the first 3/4ths of "Climbing Uphill" for Cathy.
"I'd say 'hey, hey Shiksa Goddess, I've been waiting for someone like you!'"
"Then he smiles, and where else can I go?"
"Nananana, oh Schmuel, you'll get to be happy! Nanananana, I give you unlimited time! Nanananana, just do it and you can be happy!"
"I've got a singular impression things are moving too fast!"
Norbert's riffs in "Moving Too Fast". Eargasm.
"I could shove an icepick in my eye/I could eat some fish from last July…"
Painful Rhyme: In "The Schmuel Song," Jamie describes those who "can't get out of Klimovich" and suggests Cathy is one of them because she's afraid to "go out onto a limb… o-vich." In the movie, he lampshades this with an agonized noise.
Unintentionally Unsympathetic: While most of the fandom agrees that Jamie is likable and not without his sympathetic moments, many find it hard to feel too sorry for him, considering he's the one that cheated on Cathy and not the other way around. The movie has especially added to this, particularly the line where he tells Cathy she's "being crazy", which many cite as one of the main moments they lost sympathy for him. Also, in the film, he's shown cheating on Cathy with several women, as opposed to just one like the musical implied. This almost entirely removes any credence to the idea that he legitimately loves his mistress.
The Woobie: Both of the leads, for different reasons.