This does look like a ton of fun, though the "hose" attachment didn't seem to go too far. It's also not cheap. But kudos to the developer of the thing! It's an incredibly original invention and application. Plus, since it runs in the water and is attached to something you can't go too high and there's a smaller risk of injury.
Also, I chuckled at the pun of calling this "vaporware" :)
I'm sure with a more powerful engine (which is planned), longer hoses will become possible. However, it says that the drag caused by the boat added significant stability during forward flight, so a short hose attachment actually increases the quality of the flight.
I'm not a physicist, but this paragraph struck me as incorrect (or at least misleading):
Li, however, figured that if he attached a hose to his pack, and put the engine and water pump in a separate vessel that dragged behind him, he could seriously reduce his weight, and therefore the amount of thrust needed to stay aloft.
If the engine and pump were part of the jet pack, even if the engine and water pump were weightless, wouldn't it be impossible to get enough thrust to provide lift? The propellant is being thrown back in the direction it came, so doesn't the momentum cancel out?