1- I feel this generator is very good in terms of volume of hydrogen produced per minute.  The size was a little larger than I expected from looking at the pictures.   2- The excellent design keeps water from dripping down the oxygen tubing.  3- There is no window to determine the water level.  When adding water nothing tells you when you have added too much water.  If you add too much water and run the generator, water will poor out of the sides of the generator.  4-  Changing the water is messy.  Unless you leave the drain tubing attached continuously, there is not a way to capture the draining water from the port on the back before it leaks onto the surface that the generator is resting on.  Have towels and buckets handy, or leave the drain tube on all the time.  Lastly, there was a hefty shipping /import fee tacked onto the price I paid.  Buyer beware.  Outside of control of this company and not related to generator quality.  

It serve its intended purpose.