The Brief Wondrous Life of Oscar Wao is a family saga about identity, love, loss, oppression, hexes, sexuality, and fate. Don't give up during the first 50 pages where Oscar, the fat science-fiction and fantasy aficionado Dominican-American in the ghetto, is introduced . . . it's the least interesting part of the book.
From there, you will be transported into the past and future lives of Oscar's sister, mother, aunts, grandparents, and college roommate. Those lives are, in part, shared to present the history of the evil, repressive regime of Trujillo and its heirs in the Dominican Republic. The stories shared in this book rival anything you've read about the disappeared ones in Argentina.
Any book with such a sad point needs a little levity to release the reader's emotions. Junot Diaz accomplishes that result by having Oscar be the most unRomeo-like Romeo you can imagine.
Beneath the story line, the book asks a classic question: How much should we suffer for love?
Oscar is in many ways a modern Don Quixote who is troubled by having sexual desires as well as platonic ones. The humor is more subdued, but the parallels are striking.
If all you know about the Dominican Republic is that great baseball players come from there, you'll be pleased with this story. It's sweet and sad at the same time.
If you don't know Spanish, keep a dictionary handy. You won't quite know what some of the references are otherwise.