The truth about the 380 round. whats your opinion?

I have heard countless people talk trash on the .380 for self defense but seeming how .380 chambered guns are one of the leaders on the market of defense guns, how can they be useless like some people think? The ballistics show they arent the most penetrating caliber but what makes some people call them useless? I want to hear the debate from both sides of the argument. Please include if you trust the .380 or don't trust it and also the type of gun and ammo you were using or if you base your opinion on literature alone.