Although it's a massive 30-40 hour game, New Vegas is really just an stand-alone expansion pack to the wonderful Fallout 3. If there were graphical enhancements or gameplay tweaks, I didn't notice them. But that's okay. I liked the way Fallout 3 played and more of the same can't hurt. This time around I was already well-aquainted with the mechanics so I was able to be more thorough in my exploration of the map. I managed to discover every area and, quite frankly, I'm a bit peeved that there wasn't an acheivement for that.
The story has you waking up after having been buried and left for dead. The main goal is to find out about the man who shot you. This could be interesting, I suppose, but I was a bit ho-hum about the main plotline. That's okay though. There are ton of little stories to be had all throughout the game world. Plus you get to run around in your boxer-briefs if you so choose.