hydrogen makes metals brittle and there can be catastrophic failure of valves, regulators etc.
there are only 3 significant problems with hydrogen as an energy carrier to solve before it becomes ubiquitous:
1. how to make it
2. how to store it & transport it
3. how to use it
IMO there was a time in the late 80s, early 90s when there was a chance it could be useful but the battery tech development over the last 25 years has nailed the coffin shut - hydrogen research persists because people with jobs know how to research hydrogen production.
Sure it's easier than other forms, but it's my understanding that there are some significant challenges in storing hydrogen?