This poem serves two purposes. First, Pope wrote it in response to an upper-class quarrel over an event at a party in which a young girl had her hair cut. The incident itself was petty and stupid, but the families of the parties involved were taking it very seriously. Pope, then, wrote this poem in epic form (the most grand of poetic forms) to show the absurdity of the matter, and thus reconcile the offender and offended.
That is the first function of this poem. Even though the incident is long forgotten, the poem is still very funny. But there is a greater purpose to this poem--it was written like an epic. It contains several epic elements--an epic battle (at the card game), the invocation of muses and gods, the epic quest (to cut the hair), and several literary devices, such as epic-length similes and catalogs. This is what makes this poem so great, and what serves as a testimony to Pope's remarkable genius for wit and satire.
Pope was, in my opinion, one of the greatest English poets, certainly the greatest satirist. This is one of his greatest works, and it is short enough to read over and over again without investing too much time.