The Derringer caught a lot of flak for being "Unreliable" and honestly, it is probably deserved. When you include a weapon in your deck you count on that +1 damage so that you can reliably keep up with threats as they emerge from the encounter deck.
The upgraded .32 is a vast improvement over its predecessor, requiring only a +1 over your value is not only easier, but REASONABLE. Most tests you attempt succeed by at least 1 (if you succeed), which means statistically you will do the extra damage.
But lets just say you are swinging for the fences and the chips are down and lady luck smiles on you and you get that coveted +3 or +4 over the test. Go ahead and take another action!
The ability to gain an action is HUGE. That means if this triggers once, you made back the cost of "playing out" the derringer.
If you combo this card with sleight of hand or a skill like vicious blow you also might get a turn where you just blow out a test, do a ton of damage and get a follow up action.
For most rogues, this card is worth checking out, especially if you are already packing Sleight of Hand OR Extra Ammunition.
Also, Lola Hayes likes this card quite a bit as it is a great little weapon in her hands.
Plus, who doesn't secretly want to just slap down two pistols and pretend to be Jenny Barnes? Pew-pew!