The graphics really aren't the only great thing about RDR2. The game is also fantastic for plenty of other reasons.
RDR2 is probably the best open world I've ever seen in a game, and no I don't just mean the visuals, but how interactive and alive it is. There is always something happening, it feels incredibly alive, all the NPCs have a real routine, you can see the map changing as you progress through the game, the attention to details is spectacular, it's just a really insane open world, it's very immersive and it made it one of the best games ever to me.
Yes, it's true that the missions aren't the best, especially if you play them back to back and ignore the open world, they are too scripted, but the story, acting, atmosphere, all of this was great so it helped making them interesting nontheless.
Playing an open world game that doesn't feel like a ubisoft-ish game is something extremely rare these days, and when it's also with this attention to detail (not just visuals, but everything, from side activities, how activities trigger, npc AI, everything), it's a pure joy.