There's nothing especially wrong with using a 22 mag revolver for defense. If you point it at someone and threaten to shoot them, they probably won't ignore you because of the caliber. To a dirtbag, any barrel of a loaded firearm probably looks pretty much the same.
In many articles posted in the NRA's
Armed Citizen column, in the majority of them in fact, the successful home defender usually fires a single shot and the unwanted intruders scramble to escape. In convenience store videos you can see on YouTube, where the clerk pulls a pistol on the robbers, just the pistol or a single shot usually has them flying out the door. Armed resistance in and of itself can be quite formidable.
There is a definite group-think at work on this board and other gun boards that presumes that every assailant will be a 7-foot, 300lb, hulking brute of a monster, high on drugs, enraged to the point where not even 5 rounds of .357 will stop him. I've seen people here argue that not even a point-blank round of 00 Buck will stop a determined foe.
My take is that you'll probably never need to shoot at anybody. In the majority of cases where, in the very unlikely event that you do need to fire a gun at someone, one shot or so will probably do the job. In the sum total of such rare events, a very small subset of those will involve an attacker who is willing to walk through a wall of gunfire to get at you and who will not stop, even knowing that he's already dead, and merely moving through the final 10 seconds of his life.
That does happen, sure. Eventually, when you have the means, you can prepare a defense for that. I go large, myself, and have prepared to deal with that sort of threat. Nevertheless, a person armed with a .22 revolver is probably good against most likely threats.
Yeah, I won't be able to get any other gun.
Hopefully, that is a temporary problem. It will be better to increase caliber when you get the chance. For defense, .38spl or 9mm are considered to be the low end of good stopping power.