My son is 11 now and we got him a Savage Autoloader Rimfire: model 62/64 - .22 LR, 2 Christmas' ago. Before that he was shooting a single shot bolt action .22 that I inherited and used when I was a kid. He is generally nervous when shooting pistols so I started him with the rifle. Besides that I don't own a .22 pistol but a couple of friends do. He has recently realized that the .22 pistols don't kick like the big boy guns. I like the Savage we got him, it is a semi-auto and has a mag that holds about 7-10 (I don't remember exactly). The magazine helps him learn about loading the bullets and inserting the mag correctly. Since it is a rifle it is easy for him to see where it is pointed as he is trying to cock it and get ready to fire. The safety is easy for him to reach and we stress to keep the safety on and finger OFF the trigger until he is ready to shoot. My friends that have .22 pistols both have similar looking pistols. I believe that a Rugers but I don't know the models. My son is able to load the magazine, insert it correctly and pull the slide back. With the pistols, I have to stay on him about muzzle control because he tends to twist when he pulls the slide back. He likes shooting the pistols because they are light and easy to point and shoot. The rifle is a little heavy to shoot standing and he prefers to it on a rest or from laying down. My main goal was for him to have his own gun and learn how to be safe and responsible with it.
FYI I got the rifle from Bass Pro for around $150 maybe a little more but not much.
As an NRA firearms instructor, I always recommend that parents buy the Ruger 10/22. It is a rifle that the kid will never "outgrow" and it is fantastic for learning the basics. Tube fed rifles like the Marlin Model 60 can frustrate kids when the are trying to re-inset the feed rod. Just my $0.02 worth.