With the right ammo, a .380 can be quite effective. I've got a Sig P238 and carry Hornady Critical Defense in it. Decent penetration and consistant mushrooming, from the reviews I read.
When my wife wanted an LCP because all her girl friends had one, or a body guard 380 I was against them because they are not fun to shoot, and a few other reasons. I had her put 50 rounds down range with the LCP at 25 she wanted no more, and said it hurt to shoot. Then I borrowed a friends Sig P238, she put 50 down range with it, and was ready to shoot it more.
She then decided she wanted the Sig, which she got.
My reasoning is, a carry gun is no good if you are not comfortable and accurate with it. I feel you need to shoot what you carry a couple times a month or more.
That is the same round she uses for carry. A very good round for a 380