yes Burn extremely fast in the open is its major scary characteristic
Blackpowder does not explode nor even act like an explosive unless and until it is confined.
The more heavily it is confined the more energy it will exert in escaping - there is a myth about that a blackpowder charge can only exert 20,000 or maybe 30,000 psi maximum pressure - that is nonsense - if you have sufficient charge and have it sufficiently confined, blackpowder can shred a sound steel barrel
Re the gasoline comparison - I would feel way safer with a kilo of BP in my garage than a container of gasoline - the difference ? Gasoline will come to the ignition source by vapourising, Blackpowder requires the ignition source to come to it.