Actually, if you have clay and it's got the right amount of moisture,
it does do a pretty good job, but you can't just jam it into the soil
and expect it to activate six inches at once. With patience, the
Ryobi does work well for a small garden. At least in my experience.
Fortunately I don't have any rocks to speak of.

I don't anymore. I went from gravelly soil, more rocks than dirt, to this
ugly red clay. The clay is better than the gravel, though. At least plants
grow.