I'm always curious about it too - so I always read any posts (hint to search old posts its easier to use the advanced google feature - click on the side on google.com click advance type in wine and dine program then the last box I always put in disboards.com)
so far I have read that people used it, but didnt think it was that big of a bargain - dh and I are wine drinkers - sometimes getting a bottle - sometimes just a glass - I will say that the WDW servers know how to make a perfect pour so it is not cheaper to buy a whole bottle pricewise vs a glass - -
and I will say after searching out some of my favorite wines (Rosa Regale red Champagne style in Italy -) that the prices per bottles of wine are very reasonable compared to the same wine at home (Rosa is $19 here and it was $19 in Italy in Oct)
someone posted a wine list too - and again the wine prices are very specific Disney is not going to "lose" money on it - the more expensive wines are in the 2 credit list.. 9i think the $50 bottles!)
I still might do it for a short trip