I used to work in a Whisk(e)y Bar with over 240 whiskies from around the world. Glenfarclas was a distillery we recommended frequently and their products were consistently among the most sold.
Is it a special single malt? Yes, it certainly is.
Glenfarclas is the last independent, family owned distillery in Scotland - something special in itself. It is the only distillery (in Scotland) that still uses, exclusively, old sherry casks to mature its whiskies. (Other distilleries stopped using sherry casks exclusively because of the increased costs.) It was also the first distillery to release a Cask Strength whisky as part of its normal range.
One of the great things about Glenfarclas is the range - from a young Cask Strength (60%) through 10,12,15,18,21 & 25 year old versions. (Not sure if they still do an 8 year old). Unlike many other brands with different ages, the only difference in Glenfarclas is the age. This means that the full range is about the only way a regular person (without access to a distillery's warehouses) has to taste the effect of maturing on whisk(e)y.
For example, a 15 year old whisky from one distillery will taste different to its 12 year old brother/sister not just because of the age, but because they have used different casks (typically different ratios of bourbon or sherry), or the older has been "finished" in a different type of cask.
In my humble, the 25 year old is very interesting, but I'd be pressed to pay the money for it. The 15 year old, is, again, in my opinion, the best in the stable - it represents the best balance between the spirit itself and the influence of the wood. The 25 is "woody" in comparison. But even the 10 year old makes a very pleasant drink.
One thing to bear in mind with very mature whiskies is that one batch can be different to the next. Whisk(e)y is a natural product, so varies naturally from cask to cask. While it is relatively "easy" for distilleries to provide consistent batches of younger whiskies, it is a more difficult task to produce consistent older whiskies. There may be variation from one bottling to the next. Not so much with Glenfarclas in my experience.
On the "e" or otherwise.... it has become a convention that whiskey with an "e" is Irish or American and whisky is Scottish or Canadian. But that is just a convention of the modern era. A hundred and more years ago the "e" was dropped or included irrespective of the location of the distillery. Remember, up until the 1960's the concept of a distillery in Scotland producing, bottling and marketing its own whisky was pretty much unheard of, certainly on a regular basis. Whisky bonders & independent bottlers bought young & matured whisky from distilleries, bottled it and marketed it for their own needs. Naming, spelling (and quality) was erratic, to say the least! I used to have a load of old ads for whiskies (Irish & Scottish) that would make modern marketing departments explode in a fit!
(An interesting result of this approach was the Mafia infiltration of the Whisky collectables market in the 1990's with elaborate faked whiskies and an attempt to con several high profile distilleries - with one very notable success!
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