Needing a ton (or several) of water is a problem if you want to use the device to power a truck or a plane. Otherwise, nothing could be simpler, cheaper, safer and more elegant than a blanket of water. Also, water molecules pack tightly, you would have to apply a lot of pressure to hydrogen gas to get the same density of protons that water gives you in its natural state.
The container for the water can be shipped in pieces and assembled on site. At the end you hook up your garden hose and fill it up. Well, you may have to use distilled water.
Keep in mind, even in the best case scenario there will be extensive site preparation and assembly required: You don’t just plug a 5 MW power supply into an outlet! Getting rid of around 5 MW of waste heat is also not trivial.
