My DW and I did this in May, and at $25/person, it is one of the best deals at WDW.
You're at a table with around a dozen other people, you get to taste 3 different South African wines and talk about them with the sommelier, who also talks about the South African wine industry, the table gets a HUGE fruit and cheese plate to have with the wines, and after you get through the wine tasting, you are offered more wine.
Our table went through around 6 bottles of wine all told, which is not too shabby. That averages out to a little over a half-bottle a piece (we had 11 people at the table), and the wines by the bottle were around $39 at Jiko. The artisanal cheese plate runs something like $12 there.
So, the food and drink is worth the $25, the variety of wines is a bonus, and you get a nice atmosphere, some conversation with like-minded winos...er, wine enthusiasts, and a nice background on the South African wine industry.
Then, you can go catch the Culinary Tour of Africa at the Boma desk at 4pm to extend your afternoon of indulgence.