Jeff suggested I give some information and personal taste notes on this classic whisky of Scotland which some of us tasted who attended the recent Sampler in Bardstown. This whisky is made on Islay, a remote island off the Western coast of Scotland. Other distilleries on Islay include Bowmore and Ardbeg.
A signature of Islay whisky is it tends to be very well peated - not all is, but that is the signature. Peat (a kind of soft form of coal, it looks like fudge when cut from the ground) is burned to dry the barley malt and its rich smoke infuses the malt and enters the spirit. At one time, all Scotch whisky tasted like this but with the development of modern transport, this flavour (while it characterises most malts to a degree) is today at its most robust on Islay and by common agreement Lagavulin is one of the biggest-flavoured of the bunch.
On the mainland, malt whisky often evolved into a fairly delicate, brandy-like drink (e.g. Glenlivet, Balvenie, Macallan). With the development of modern methods including transport to ship coal, less and less peated malt was used to make the drink, the peat was increasingly dispensed with in favor of coal and later electric heat in Speyside and the Lowlands distilleries. Probably due to their remoteness, the Lagavulin and Ardbeg distilleries retained the traditional big peaty character which (to a good degree) makes scotch what it is. This is an acquired taste but many people come to enjoy it.
Lagavulin is marketed in a hard-to-find 12 year old version (drier, lighter than the 16) and 2 versions of the 16 year old. One is finished in Pedro Ximinex sherry casks (a rich sweet Spanish wine) and the other may employ some sherry cask aging but is not as sweet. The Pedro Ximinex version is called Distiller's Edition. Both are excellent. The one we tried in Bardstown was the Distiller's Edition. It is heavy-bodied with a huge "peet reek" as the Scots would say. It is sweetish, perfumed from the rich sherry (violets, Turkish delight) with a deep, persistent smokiness. Also, it seems to have salty and "seashore" edges which may reflect the effects of local weather on maturation (the warehouses are right by the coast in many cases). It is an unusual taste but one can see that without the offset of the peat smoke, the drink would be blander and indeed some malt whisky can be said to be bland today. What made it "Scotch" (as I said, and in my view) was the effect of the smoke on the palate.
Small amounts of Islay and other smoky malt whiskeys are added to almost all blended scotch to impart some of the flavour, but often in very small amounts. Johnnie Walker has a good Islay flavour in my view, especially the Black Label. While the flavour of malt whisky of this type is very assertive and completely different from Bourbon, one can see certain analogies. In Bourbon, the rye element in the mash (where rye is used) adds complexity to the taste, as does the char flavour from the barrel. In Islay scotch of the Bowmore, Lagavulin or Ardbeg type, the complexity derives from the adjunct of rich peat and sherry flavour to the malty sweetish barley spirit. So both drinks can become fine spirits through achieving complexity but do so in different ways. (Although I always felt the burned wood taste of some old Bourbons is quite akin to the peat smoke flavour of certain malts. I have said earlier I believe early U.S. whiskey makers may have charred the barrels inside to obtain in the palate the smoky tang they recalled from Scottish whiskey - many of those whiskey makers were Scots immigrants or the families of whom were not long in America from Scotland or Scottish-influenced Northern Ireland).
For those who want to try other peated malts, I recommend the 10 year old Ardbeg which has a classic lemony/smokey character. Bowmore is good too, it has a smokiness which is sometimes called "fern-like" and may derive from the sandy, crumbly peat used to smoke the barley malt. It took me many years to acquire the palate for Islay whisky. I enjoy Lagavulin but only occasionally, it is too "big" for me as a regular dram of scotch whisky. I am not knocking non-, or little-peated malts, many have their charms and virtues, but to me Lagavulin is THE traditional malt scotch whisky and likely defines what most malts were like 50 and 100 years ago.
I welcome other views.