i'm a fairly big guy and i learned to shoot on my compact .45
i'm not the best shot i know, but i'm FAR from the worst, even amongst the people i know that 'shoot all the time'
from a money standpoint, yes, .22 is definitely the way to go
but i was always taught with anything, you're better off practicing with what you're actually going to be doing
if you want to build a better jump shot on the basketball court, you don't start practicing with a doorway hoop and tennis ball
if the person is going to try to teach themselves, then i understand a .22, but if you've got an experienced shooter with you teaching you how to shoot and you can afford higher caliber ammo, i don't see the advantages of learning on a smaller caliber
especially if you're going to purchase the pistol you're learning on