I've only just started playing this. Fantastic game - prefer it to Skyrim at the moment.
One thing I find incredible, is how the they've nailed the feeling of isolation. It's a very lonely, and sometimes scary, experience.
I love the entire series as a whole. Even though I have never exactly finished any of my saves I always just go around and meet all of the NPC's and doing all the side-quests. I would recommend the series to anyone who likes RPG's or is interested in a setting of a region ravaged by nuclear weapons (Fallout NV isn't that bad compared to Fallout 3). I even have my own character named Dexter who goes around chopping people up with my unique knife.