Yes it's explosive but you can't see it, for those who think what you can't see can't hurt you. It's property of burning invisibly makes hydrogen uniquely dangerous.

As far as its power density I believe its the best, when mixed two to one with oxygen, that's why its the preferred fuel for rockets.

But you can't beat the exhaust, water vapor!

A big problem is where you get hydrogen. You end up with something like making gold out of lead by mixing it with platinum.

I give hydrogen power a thumbs down.