There are lots of apocryphal "the .25 ACP ain't worth $hit" stories. Some of them may be true.
It's a little less powerful than .22 LR rimfire, but the cartridges are a lot more expensive.
I have no personal experience using one, but just based upon common sense I believe that if I had one, I'd trade it in against a .380...or even a .22 LR.
I suppose that at flesh-burning distance, a fusillade of .25 ACP might be a deterrent, if no drugs were involved. A hit to an eye socket would probably stop a fight.
I wouldn't carry one, though.