Half a liter in a few hours is way less than a cyclist needs. This is renewable and a bottle isn't but I can pack much more water in the volume of the device and get other water when I stop. If I can't find water maybe I'm in bigger troubles than half a liter can save me from (in a desert, really?). It's not worth it. However, put a bigger device on a car or on a boat and that can be useful.
Where my curiosity lies is in energy consumption. There's a power button on it obviously, so how much power does it use? I'm not an expert in thermodynamics/rates of condensation but I know my dehumidifier is a freakin power hog and it's doing exactly the same thing as this. My guess is that power consumption is the biggest hurdle here.