Kosher wine has improved dramatically in the last decade, and now the best of it can take its place beside the best non-kosher wine. These days, makers of kosher wine insist their wines aren't just for Passover anymore.
Traditionally, kosher wine has not been fine wine. Most of the Jews fleeing Eastern Europe 100 years ago came here by way of Ellis Island. And the only kosher wine made on the East Coast was a syrupy dessert wine based on Concord grapes. As a result, "kosher wine" came to mean something sickly sweet that did not go well with any food, but had to be consumed by Seder edict.
Besides a few arcane rules about cleanliness and who can do what with the grapes and the wine, one key rule is that for a wine to be mevushal, or universally kosher (so it doesn't lose its kosher status if a non-Orthodox person serves it), it must be heated during production-a technique that in the past would have ruined the aroma of any fine wine. Such wines were more broadly marketable than kosher wines that were not pasteurized, but some producers, Hagafen among them, felt the heating process too deleterious and they rejected it.