It is one of my favourite games ever. And I don't even like rpg's in general.
What sets it apart to me is the atmosphere and story.
Every place tells a tale. Walk into a room and often you can piece together what happened, find audio snippets or logs about the days before, it just has so much attention to detail that it immerses you in its world.
The games themselves are taking place in what the people in the sixties would think our world would be like today after a nuclear Holocaust. This means laser weapons, robots and hover cars, Intelligent AI but with old monitors and OS's. It's just really imaginative a lot of these things when you see it in action.
A lot of it comes from the little things though. You are basically learning a whole new world and need to cut off your knowledge to modern society. Looting money is pointless as the currency is now bottle caps for example. It's just something you have to loose yourself in and it is a game best enjoyed while deviating from the main path and explore instead. That's where the real meat in this game is
I remember that one place that you enter and find a skeleton lying on the floor while holding two cases of bullets with a gun close by it's side, right by the entrace, the skeleton is right there in front of you when you enter the place.
I thought to myself: "Well, the game designers just wanted me to grab some ammo so they put that there for no special reason, like it goes for most games".
Then I go inside, and I pick up and hear the audio logs and hear the narration of a man as he struggled to stay alive against the feral ghouls that took over the place.
The last audio log had him saying how he would grab the remaining ammo and run outside to get away from the danger.
Once I finished raiding the place, I was ready to leave and headed back to the entrace. I looked back at the skeleton holding unto those ammo cases and that random skeleton didn't look so random anymore. That skeleton now had a story and seeing him lying there told the end of that story, without audio logs and without anyone having to tell me what happened. That man was killed right before he could escape the place.
That is a whole different level of storytelling.