As a sherried scotch drinker, by extreme preference, and Not An Islay Guy At All, generally.. the 15 Bowmore Darkest is quite a nice dram. The more sherry the better for me, but I've not had the NAS to compare it to.
What I was reminded of was the Talisker Distillers Edition, only younger and sweeter. (The Distillers Edition is a (imo) very non-typical Talisker)
My standard drinking style is a slosh in a glass, no ice or water, and Bowmore Darkest works just fine that way.