At its most clear-cut and varietally distinctive in Alsace (where it is never spelled with an umlaut), this variety produces very aromatic wines that are naturally low in acidity.  The Gewurztraminer's famous spiciness is derived from terpenes, which are found in the grape's skin.  The grapes have to be ripe, otherwise the wine will just have a soft rose-petal character, and the wine must not be acid-adjusted or the spice will lack breadth and potential complexity.

Info : The Sotheby's Wine Encyclopedia 4th Ed by Tom Stevenson