Where once Portuguese wines were too often dirty and dull and oxidized—really, Port excepted—that's all gone now. Everywhere, the winemaking is vibrant and fresh. Still, one vestige of the past persists: Prices are lower than anywhere else in Western Europe, where Portugal is the poorest country. Not surprisingly, many Portuguese are disinclined (to say nothing of unable) to pay the sort of high wine prices we Americans have come to accept as inevitable. Because of this, price is no barometer of wine goodness. Some of Portugal's best wines are implausibly cheap, while some of the most expensive—though not all—are merely big fruit bombs laden with a lot of oak. So how do you choose? Wine Spectator's Matt Kramer explains.