Natural coffees can be funky, as can Sumatras. So one might expect a naturally-processed Sumatra to be particuarly funky. It might be, but the one I have from PT's is remarkably clean.
PT's tasting notes are rather involved, as if folks need to be reassured when presented with a coffee with this processing method and this origin. The notes say "A complex and full coffee that brings to mind deep red wine, with heavy, sweet notes balancing out into a spicy character. In the fragrance and aroma, dark cocoa and black pepper lie heavy over a soft berry or cherry like scent. In the cup, the sweetness opens up into dark cherry, blackberry, and hints of banana. The bakers chocolate deepens and the spice note hints slyly at clove."
My simplified impressions are this: when the coffee's black, the dominant flavor is low-toned berry. Similar to the berry in PT's Ethiopian Sidama, but with less acidity. It's not really like any berry I've actually eaten, though I suppose blackberry would be the closest analogy. The sweetness is earthy but not in a Sumatran fallen-leaves or alpine way--it's like the sweetness of a beet, or a sweet potato, or a persimmon, or a Golden Yunnan tea. Maybe one of those terms sticks.
With cream and sugar added, it tastes like butterscotch candy
So, yes, nice coffee here. I liked it best as paper-filtered drip.