This is one my long-running favorites, but never got around to write down a review of it. Let's give it a go, shall we?
Bottle bought 2017.
1.6 (Mahogany)
Nose
Marmalade, oranges, reasonably spicy sherry. Rich, deep. A bit of raisins and winey notes. Nutmeg? Yeah, maybe nutmeg.
Palate
Oily! Not nearly as oily as the 25-year-olds I've tried, and not much of the same waxiness. Still a nice thickness to it. A big spoonful of spice with some pepper lurking at the back.
Finish
Here, it all comes together beautifully. There's hardly any distinct flavors to pick out and name, but the outro is very pleasant. Starts off slowly. Kicks in with some extra heat after a few seconds as many good whiskies do, and sticks around for quite a while. It's soft, fruity and slightly dry.
Given the (both excellent) 12 year and the 25 year old OB Bunnahabhains, I think the 18 year old makes a lot sense. It's a clear step up from the 12, but not on the level of the 25. They're all similar but with a somewhat linearly increasing richness and intensity. The 18 might be a sweet spot when it comes to price/quality though, as the 25 comes with a steep premium for that extra quality. If you, like me, are ready to pay a little more to get an excellent whisky, the 18 might be the best bet in the bunch.
I'd like to score this a bit into the 90s, but it's after all a pretty standard dram. It does not have a huge "wow" factor, it's just a pretty damn good whisky. Great, even! For a reasonably available, well-made standard bottling that doesn't put you in too much personal debt, one of the best.
It has to get a lower score than the 25 (2017 version), so 88 will do. I usually don't pit whiskies against others review-scoring-wise (it's inconsistent, impossible and will quickly lead to insanity) but against other OBs in the same range, I'll make an exception.
Score
88 / 100
0-50 Subpar
51-60 Drinkable
61-70 Decent
71-80 Good
81-90 Great
91-100 Fantastic