Dustin Hoffman and Meryl Streep don't make a single mistake in this movie, and neither does Justin Henry, the kid actor who plays the child torn between two parents. Hoffman plays a workaholic dad who is stunned (when his wife abruptly leaves him) to find himself the single parent of a child he barely knows. The film is beautifully book-ended between two telling events: getting breakfast for himself and his son at the beginning, we watch Hoffman hilariously, angrily, and ineptly screw it up, while by the end father and son have a quiet dance of cooperation and guy-ness all worked out. There are so many similar pivotal moments, such as a playground accident that sends Hoffman, child in arms, racing the streets of NY to the emergency room. Hoffman finds he cannot balance the demands of parenting with the high-pressure demands of his job in the advertising industry - and he chooses parenting. Then, like multitudes of single MOMS before him, he discovers how difficult it is to make ends meet.
Meanwhile, his wife, freed of parenting responsibilities, is on her own trajectory, is 'finding herself,' and becomes financially successful. Also, she watches how husband and son are doing, spying on them from a distance, and we sense her loss and her pain - yet also her pride that Ted (husband/father) is actually coming thru for the kid.
Then comes the custody battle at the end, the wrenching scene in the elevator - and Streep's final comments to the judge. Wow. Kramer vs. Kramer won 5 Academy Awards. Filmed in 1979, it is just as relevant today as it was 25 yrs ago.
People who declare this film is one of the finest movies ever made aren't lying.