Extremely good for weight and extremely poor for volume. To reduce the gasses volume storage is usually either highly compressed (200-700bar) or cryogenic (30K), like in the space shuttles tank.

In both cases the volumetric density is still quite poor, cryogenic is about 70g/l, which is actually less than the weight of hydrogen chemically bound in a liter of gasoline.

There exists some concepts of storing hydrogen chemically bound, e.g. to hydrocarbons or metal hydrites which release the gas on high temperatures (100-200°C).