I rarely post negatives here, but since you are asking opinions - if you've done wine tastings before, I wouldn't recommend unless it is a rainy day at sea. While it was nice to taste the wines they had on board, since they are only giving you one of each wine family (Merlot, Reisling, Chardonnay, etc)...you only sample that one.
Personnally for 1 hour of "entertainment" for $24 - DH and I will not do it again. But remember, we've done other wine tastings. And perhaps our group (and the room was filled) was sleepy, but the whole thing was a little dull. I would have rathered spend $24 on a single bottle of wine, sipping up on deck under the stars some evening.
Just my opinion.