Philosophically...
Either/Or is a work by the Danish philosopher Søren Kierkegaard, first published 20 February 1843 under the pseudonym "Victor Eremita," or victorious hermit. As it is usually interpreted, this psuedonym is not a direct commentary on the work in question (as many of Kierkegaard's chosen pen names clearly are). Rather, it is thought to be a sort of flippant personal statement by Kierkegaard, reflecting on his tendency to isolate himself in his room like a hermit into the late hours, writing voluminously for several years at amazing speed. Either/Or, for instance, was published in two volumes amounting to over 800 pages.
Eremitus 'claims' to have chanced upon some papers, written by two different authors, whom he calls A and B. A and B's papers are clearly meant to represent opposing views on the meaning of life, more as in how to live it. One commentator, Dr. Anthony Storm, posits that Kierkegaard means to "draw his reader out of his preconceptions and away from the influence of the then very pervasive Hegelian system." At the time, this was some of the most influential philosophy in existence, and Kierkegaard was undoubtedly annoyed by many of its pretenses. He thought, for instance that Hegel's theory of dialectic progression (a thesis yields an antithesis, which then yields, along with the thesis, a synthesis or unity, which in turn becomes a new thesis), threatened the validity of propositional truth, that is, the law of contradiction. However, it is also observed that Kierkegaard does not outrightly set A and B at each other's throats, but rather seems to seek their reconciliation. Reconciliation is not an entirely alien concept to Hegel's system. In addition, Kierkegaard also proposed a triad, in which the third element was the religious sphere. In Hegel's theory, the ultimate unity was God.
A and B
A lives in what Kierkegaard called the aesthetic mode of existence. A's writing is often accused of being incoherent, purposely so, in that Kierkegaard formulates the aesthetic view as godless and ammoral, and therefore inevitably disorderly. A himself says "My soul is like the Dead Sea, above which no bird can fly; when it has reached midway, it sinks down in death and destruction." A's papers inlclude a diary of a seducer, essays on drama and literature, and an essay on Don Giovanni. There is also an essay entitled "Rotation of Crops" in which he asserts that boredom is the root of all evil, attempts to advise his adherents how to avoid ever feeling bored. Kierkegaard's prose here is clearly ironic; meant to suggest that such an endeavor is both ridiculous and impossible.
B's papers are letters to A. B is otherwise known as the judge, or Judge William, who writes on marriage. In his advocacy of marriage, he symbolizes the ethical stage. Marriage is a forward-looking commitment related to Kierkegaard's concept of repetition, contrasted with the backward-looking (aesthetic) concept of recollection. In his writing, the judge tries to persuade A to take stock of his life, despair over its lack of balance; in short, to become more ethical. Get married maybe, have a few kids. B diagnoses A's unhealthy isolation as the sickness of the century, to which he compares the temperament of Nero, emperor of Rome. As a man, B theorizes that Nero was consumed by the aesthetic while on his throne, which in fact made him not a man at all, but a child. Although Emperor of Rome, Nero 'feared' a bold look from a human being to the extent that he would have this person destroyed: "Nero has no murder on his conscience, but his spirit has a fresh anxiety."
A reconciliation?
The second chapter of Either/Or, Part II is entitled "The Balance Between the Esthetic and the Ethical in the Development of the Personality". The judge begins by accusing A of not being able to make the either/or decision, that he is non-committal. The judge does not want a blurring of the two, but wants to transform the former by taking up the later. This is where Kierkegaard seems to falling into the Hegelian trap; the 'carrying over' of elements of the thesis into the synthesis is an essential part of true dialectic. In addition, near the end of Victor Emerita's preface to A and B's papers, he (Kierkegaard) speculates that A and B are in fact the same person, writing during two different periods in their life (A presumably being the younger version of the same man).
What is Kierkegaard trying to say then? Kierkegaard hated the form of philosophical treatise (Concluding Unscientific Postscript was in fact written in mockery of that style); this makes it very difficult to interpret his meaning in much of his work. However, from the title, it is clear that he is writing about choice (life choices), from the content it is evident that the choices consist of a type of epicurean hedonism and staunch ethics, and from the recurring themes it seems also likely that Kierkegaard wanted to argue for a type of qualified balance. Doesn't sound like much for 800 pages, but I recommend taking a look at the actual text. It is usually sold in excellent excerpted form with commentary.
I used: http://www.sorenkierkegaard.org/ and the Kierkegaard Reader. Editor: Chamberlain, Jane; Editor: Ree, Jonathan Blackwell Readers; Paperback; 416 pages; Published: June 2001; Blackwell Publishers; ISBN: 0631204687.