IMO, the manga isn't much interesting until that spider family appears... The appearance of the Hashira and upper moon made it better, and from now on, the story is just more fun. I guess that the anime would be more intense in the next season as well.
Some big names in Shounen Jump are also slow starters that aren't intersting until they reach vol. 5-6... Bleach and Rurouni Kenshin were like that. I remember that in Bleach case, the publishing in Thailand hadn't cared about the series at all and they hadn't bought the license of Bleach until the shinigami captains were revealed in the story.