You cannot ignore fuel cost and investment to handle the new fuel. We'll see what happens, but the most compelling thing to me seems to be the fact that it burns hydrogen and not kerosene which seems to be more environmental friendly, but I'm no chemist.
Burning hydrogen releases water vapour, while burning fossil fuels release carbon dioxide and water vapour. So, you could call it indeed more environmental friendly if you consider carbon dioxide harmful.
However, hydrogen doesn't occur on Earth in a pure state (at least not in mineable quantities). There are no hydrogen wells.
Creating the hydrogen (for example, by electrolysis of water) is expensive and generally a net loss of energy. Maybe storing energy in hydrogen is feasible if it's generated with excess nuclear or solar electricity.
> burning fossil fuels release carbon dioxide and water vapour
Either I have completely misunderstood something, or fossil fuels release only CO2 and H2O under ideal conditions, which never happens. Add to the fact that any jet engine is unable to utilize any after treatment systems to remove harmful products. I am fully aware that hydrogen is rather expensive to produce, but I think it's possible that nuclear energy, or (as you mention) excess solar/wind power is several magnitudes cleaner than even the cleanest burning fossil fuel engine (including all the resources it takes to pump it up and refine it).
