When the rules provide the three options of how to determine a fumble (http://paizo.com/image/content/ItemPacks/PZO3004-Rules1_500.jpeg) it states "While the first is recommended, as it is the one that least penalizes the players, the latter two are a bit simpler to adjudicate." This may lead some people to believe that "simpler to adjudicate" is worth a little more strife for the players. BE WARNED.
Our GM went with option #3: Rolling a 1 meant a critical fumble. Anyone with multiple attacks is going to get screwed. Like, you're out of the encounter or DEAD screwed. One PC rolled a 1 and pulled a card that was "Roll to confirm the critical against your AC and you crit yourself." The 8th level PC killed herself with a Scythe. Stupid. The big boss fumbles and breaks his only weapon? Just as stupid.
Maybe I would have liked these cards more if we went with the standard option. The more powerful you are the less likely random dumb things should happen.
You want wacky randomness in your game? Let your PCs stick fight kobolds with Rods of Wonder. I'd pass on these cards.