Until it replaces every function and convenience of existing technology, at a comparable price, it will not be good enough for most people.
While Hydrogen cell cars haven't really taken off so much, one thing that James May said during a Top Gear piece on them was, "It's the car of tomorrow, because it's already the car of today". Of course, he was speaking in terms of function, features, convenience, range, time taken to fuel, etc...
IIRC, it's the cost of producing the fuel that makes it prohibitive?