The game just released. Between Antihero, Civ VI, and a moderate (and probably temporary) addiction to Arena of Valor, I don't know how much time I'll put in to this at the moment, but I'll update when I get around to exploring. For reference, Eternal is probably my favorite digital CCG, so that's the bar that Pathfinder Duels would need to hurdle.
Edit: My initial impression is "meh." I played the tutorial and one more game. So far, the cards are fairly generic. You have your typical attack/defense, and keywords like "haste." The game plays in portrait mode, which I actually like. Resources generate automatically, like Hearthstone. I do like the simultaneous play, and that the spot a card is placed on the grid determines its priority, but I don't know if the game feels all that special. I love seeing beloved Pathfinder characters and art, but if they were removed and replaced with non-licensed generic fantasy art, I don't know that i'd have much interest in the game.