Tried a little experiment that I saw Ralfy do in one of his reviews: tasting side by side a freshly poured glass and one which I added water to ~30 minutes earlier and had let it rest. My choice of whisky was Glengoyne 21.
Neat:
Nose: sherry and oak. Sweet, like raw sugar but not overpowering. Milk chocolate. The nose is subtle at this strength, no issues getting in there. Very pleasant, but if anything a little monotonic.
Taste: Very mild entrance, a little sweet, no spices, no alcohol burn. More sweetness develops, along with a silky texture.
Finish:Long and sherried, with an oaky after taste
With water:
Nose: The oak went away but the sherry remains. The raw cane sugar smell is a little tamed. More crisp, but less intense.
Taste: Maybe too watered down now, but interestingly some spicy flavors develop.
Finish: A bit bitter and not as long. Flavors linger, oak, some bitterness, some sherry.
Overall very good, although I think I added a bit too much water to the glass. Seems rather delicate. Actually, I would call this one a "delicate sherry bomb".