Scotch Malt Whisky Society's Shape Shifter is certainly one of the most memorable young (10yo) whiskies I've tasted. Underripe strawberry, peach, vanilla, white chocolate, lemon curd…and that 60% ABV gives it a lot of body and intensity.
I do wish distilleries would release more cask strength bottlings. 40% is rarely ideal for a whisky's mouthfeel.