Interesting - the buckwheat gives it a unique flavor. I'm not a huge fan of rye whiskeys, and this is lot like a strong rye - spicy and bitter (although definitely not an astringic bitter). There's also a strong note on the nose and palate that I can't place. Perhaps it's a woody note, but it's different than any wood note I've experienced previously.
Based on a previous comment, I spent time nosing the empty glass. It was exceptional - a cross between caramel and campfire, which is odd, since I didn't get either on the palate.
I gave it a 3.5, because strikes me as a well crafted whiskey, even though it's not my favorite - too bitter. But I'd recommend it highly to rye lovers.