Grassy on the nose initially, with whiffs of marinated artichokes, Italian style. Definitely an acidic aspect: mixed pickles, light vinegar, sour wood. Speaking of: not a whole lot of oak on the nose (it provides more of a warm background than a front-and-center impression) and not a whole lot in common with the regular OB's (12, 15, 18). Honey, limestone, orange peel, a tangerine that's beginning to go off. Interesting, if a bit shy without water. Overall dry impression, I expect some tartness on the palate.
Still a bit harsh without water. Tart, yes, but with some juicy sweetness in the middle. I say this needs...
...water! Oh yes: more honey, more aromatic old wood, more orange juice, less mouldy fruit. Now a dusty, leathery side appears as well. The age is starting to show. Way to go. The palate, much tamed and improved with H2O, remains unconventional with little to no mass appeal, i.e., tart, acerbic, strong, still a bit fiery, with all the sweet aspects packed smack in the middle, tapering off into a medium-long finish that mainly offers warm wood and honey notes that shade into maple syrup.
I find this highly interesting, as I had previously thought that the (less sherried) 12-year-old OB was borderline bitter, whereas the richer, more sherried 15- and 18-year-old versions were very pleasant. So Cardhu seems to need quite a few sherry casks in the mix to lose its rough edges. Verdict: an unexpectedly edgy and fiery Diageo Speysider that shows what the distillate can provide as a solo act: a rough number that might even some win over some cask-strength Bourbon fans.