They did such a good job with the story for RDR2... But the online has definitely fallen short. The devs have definitely tried to make the online similar to that of GTA Online, which just does not work in this case. Even the simplest things such as hunting are affected. There are so many things to do and places to go during the freeroam of the story, and almost all of it is thoroughly enjoyable.
I'd say make sure you know what you're getting before you buy, if you're looking for a fun story driven game full of side quests and other exciting oportunities then this is your game. However, if you're looking looking for a wildwest version of GTA Online, you will be very disapointed.