I have a SR22 for training. It seems to be reliable and safe. Really, the only issue is 22 LR reliability and capability.
Rim fire ammo is not as reliable as center fire.
Of course, 22 LR will be weaker than you might want.
Do not count on bad guys being afraid.
A larger heavier center fire pistol might be just as easy to shoot.
Still, a SR22 is still better than unarmed.