I've got one that my almost 7 year old son uses. My 4 year old also uses it, with a little help. Great gun, no problems ever. The 7 year old runs it on his own and fits him fine. Triggers good, and I like him learning on a single shot. It slows him down when he gets excited shooting. I like it better then the crickett.
The only thing that he has "issues" with is the peep sight. I have a hard time convincing him not to get his face right up to it. It's got the small aperture, so he wants to get close to see the big picture. It's not a problem with this firearm, but if I don't break him of the habit, he's going to scope himself when he steps up to something bigger.
A couple pics of him running it.