I recently did a tasting vertical of Glenfarclas 12, 15, 17, 21 and 25 along with the 105 NAS. I have full bottles of the 12, 17 and 105 NAS and got a sample set of the others to see what I was missing. My feeling is that I was not missing much. It seems like GF peaks at around 17-18 years with their production offerings. I suspect that any really good older barrels are being sold as single cask offerings. The 12-year old expression is a very solid whisky at a great price. It is a great entry into sherried whiskys and the abv is what you expect at this age and price point. It's not a great whisky and it's not one of my favorites or what I would reach for but I have a weird relationship with sherried whisky. I like it more at higher abv than watered down. This is the beginning of sherry bomb territory though... kind of a gateway to heavily sherried whisky. It's totally respectable for what it is and what it is trying to do.