The type in the picture are easy to use. They have a lip on the back so they don't slip forward. For a low, level wall, as shown, he can do it. Much higher and I think you'd need something for drainage.
I used those to make a little raised bed for herbs. They don't corner well (the tighter the corner, the further back the next course sits).
The dirt behind the wall will compact and sink over time (unless you do a better job than I did compacting to begin with).
Go to Lowes or HD and putz with them, or buy a few dozen to see if they'll work for your yard.