It was really fun! Rolling unlikely outcomes made things super unpredictable and fresh, like when a wimpy character decides to fight instead of fleeing. It had a tendency to create great moments when it wasn't clear what the best course of action was going to be.
I think it could be easy to overuse. For example, I was tempted to roll every time I had a player bargain, without respecting their skill check. I found them super duper helpful when I was split or for more inconsequential, character charm moments. The meeting and fight cards in particular were very useful.
The only miss, strangely, were the mood cards. Try as I might, it was just too hard to subtly infuse a character's words with fatigue or stress without piquing my players' interest, prompting intense rounds of questioning. "This NPC must be tired for a reason" they all think, owing to ancient gaming instinct. For such a broadly applicable card that I would like to use a lot (essentially every time the players meet a character again) it's too much of a burden to give them a satisfying answer in the moment as to why someone is stressed today and they love jumping to try to "help". I'm not sure whether I should be changing my approach or tinkering with the card itself, swapping out emotions for ones which evoke less in my players.
I suppose that criticism comes down to "these cards create moments every time, don't use them if you don't want something to happen", which is far from a knock against them, more of a word of caution to overeager GM's who might be inclined to lean too hard on them.