I'm far from a coffee snob (I buy most of my coffee from Costco) but the problem is that starbucks over-roasts their beans, so, anything without sugar and milk added tastes bitter.
What it actually reminds me of though, is the taste of a shot that was pulled then stored in a fridge. I wouldn't be shocked find out that they store excess shots for later drinks and they end up even more bitter.
It’s still a pretty dark roast, but way more tolerable.
Still expensive for what it is.