I am afraid the critics are correct. Unless you can find a big pool of elemental hydrogen, that isn't already in a compound, it would take more energy to manufacture than you can get out of the process. Coal, petroleum, natural gas, nuclear fission, and falling water work because the fuels can be found that have high amounts of potential energy. E. G. the rock is at the top of the hill, ready to be pushed over.
Where as, the hydrogen in water, is already at the bottom of the hill. You have to put energy into the process to split the water apart and extract the hydrogen. E. G., you have to push the rock up the hill before you can roll it down.
