The “auto-stop” mechanism is pretty much designed only for rice. That doesn’t mean, however, that rice is all you can cook in it. We’ve used ours (along with a handy tray insert that came with the cooker) to steam corn on the cob, and it comes out great; you just have to time it yourself and manually turn the unit off.
My understanding is that the mechanism that automatically turns off the rice cooker is basically just a temperature sensor. In short, you add the rice and water at the start, and the water comes to a boil; when the sensor detects that the temperature is rising above the temperature of boiling water, it intuits that the water has all been absorbed or boiled off, and so it turns off the heating unit, at the perfect time. Pretty ingenious, but if you’re cooking something that could theoretically boil all day, the sensor will never trip, and I can imagine the cooker could get damaged by burned food if you have something in there that burns below the boiling point.