Better then nothing and no bad guy will advance on her if she's getting constant hits in his face,neck and upper chest area with it.
As noted above, "nothing" is an awfully low standard against which to compare something for self defense.
As for getting constant hits in the face, neck, and upper chest area, you know, we just don't seem to see that result occurring with much frequency.
Yeah, people successfully defend their homes and themselves with .22s. They have also managed the same feats with BB guns and unloaded firearms.