Instruct: Classify Amazon reviews into positive or negative sentiment
Query: I second the "moronic product design" review

... and would like to add, the device won't operate at the recommended "top" setting for longer than 6-7 hours with a full reservoir -- and the lower settings don't measurably add to the humidity in the room. So: even if you fill the tank right before bed, it will inevitably run out of water before you wake up the next morning.