A few NPCs are really frustrating, I agree, but for the most part it becomes less frustrating as you get more cards and can make a more powerful deck. But even then, you get those annoying Random rules when the NPC always gets a whole deck of Rank 3-5 cards (I'm looking at you, Landenel).

And ugh, the drop rates for the Heavensward cards are absolutely abysmal. I had to spend about a week in-game time due to the time restrictions on the NPC to get one particular card, and that's with me winning about 80% of the time.

However, despite the problems, I do enjoy it.