I played the story on PS3 back in 2013 then picked up the PAC version and only played online that time around. I did put about 200 hours in to it which is a lot for me, j probably have 4 or so games with that many hours or more.

If you're looking for story it never got good, particularly because your protagonist is a silent insert with no supporting NPCs to carry it, but if you're favourite part of story mode was the general exploration and open world stuff, it's pretty good. I sometimes played with friends but I think 90% of the time I put in was mindless time wasting which it was good at, although I was a teenager and I'm not looking to waste time like that anymore. I also got into modding it in about 2017 and had a really good time with infinite money and cheating benevolently which probably got me an extra 100 hours of enjoyment out of it.

I think it had a golden age which you've missed. The first 6 weeks it was out, it was totally broken and then for maybe the first year and a half it was really low on content compared to story mode. Eventually the first wave of heists and tools and resources to support race / minigame makers came out too and that was a great era. Eventually though as players left more and more over time it was becoming more and more targeted at those few "whales" who were probably spending thousands on the game, with all content becoming inflated in cost to sell shark cards. By the time I dropped the game, it was practically impossible to progress without buying the digital currency, and any money exploits or cheater's were gone, leaving only the destructive cheaters. I have no idea if this has got better I haven't touched the game since maybe 2019.