Wikipedia says the electricity->H2->electricity efficiency of a fuel cell is 30-50%. That's much, much worse than batteries. Sure, refilling is easier, but the environmental impact of H2 is too large.
Barring a major breakthrough in the efficiency of hydrogen production, such as low-temperature cracking of H2O as a waste-heat recovery process, I favor lithium and lead-acid batteries over hydrogen fuel cells.
http://www.hydrogenhighway.ca.gov/fa...elltowheel.pdf
The above link indicates that if you're using grid electricity to produce hydrogen, HFCV's pollute much more than conventional gasoline-powered cars. Better to buy a gas-sipper and a windmill, than a HFCV.