It's hard to give an exact number. It depends on how you define 'worth' in terms of episodes. Some might say it's worth a lot, depending on how much they enjoy the story and characters.
The main plot points include the birth of the super siblings, their training as heroes, the death of their father which brings them back together, and the looming apocalypse they must prevent.
Well, the Umbrella Academy full story is quite complex. It begins with the extraordinary birth of the seven children. Luther has super strength, Diego can manipulate knives, Allison can manipulate reality with her words, Klaus can communicate with the dead, Five can teleport and has time - traveling abilities, Ben was able to summon tentacle - like creatures from his body, and Vanya was thought to be powerless at first but later discovers she has the most powerful abilities. Their journey involves dealing with their past, like their strict upbringing under Hargreeves, and present threats to the world.