I had a hard time getting into Destiny 1. Probably never would have stuck with it, except a bestie in California is head-over-heels for it, so it was our go-to co-op experience.
I'm actually enjoying Destiny 2, where the Public Events and side adventures have added to it. It also feels better balanced, overall. There's likely some very deep game balancing happening that's not visible to players at this point.
The guy that went back to Destiny 1 after declaring 2 a failure is almost certainly falling prey to judging Destiny 2 on 1's merits, critiquing the game he wished he'd had, instead of the one he's got.