I am also playing it on PS5. I'm about to leave the third camp so quite a bit in. I find the story to be surprisingly engaging for an open world game. The info bits about the virus, about Sarah and the conspiracy stuff from Copeland is pretty good. Horizon engaged me less in the middle part, for example. That picked up rather late. Days Gone keeps drip feeding relevant story bits.
Somehow the mission structure doesn't bore me, I love riding around and most objectives are short. Kill 5 guys, save hostage. Find something. Camps are fun and have 20 enemies at most (less if you do it stealth I think), some have only 8. Hordes interfering is frightening and forces a change of plan, but can also work to your advantage. I would say the game is too easy though, should've started on a higher difficulty. There is always enough resources to the point you likely never run out of anything. With the skills I have right now, I notice I can take on bigger groups more easily. A silenced Sniper with points spent on Focus seems to be OP.
Right now I think this is the second best PS4 Sony exclusive after GoT. I am playing it more often than the likes of God of War and Last of Us. I love the sandbox, the atmosphere, the constant danger popping up, the music bits... I never played the vanilla release, but this game is reviewed way too harsh.