This is a big and awe inspiring game at first, unfortunately you won't want to look too closely at the details.
Context, story and characters: This is covered by Gamespot. The various grey moral choices make decision making more than just what choice gets me the best loot.
First thing you'll find is that the game seems gigantic. This is evident from the perspective the game sets you in as you wander the small town of Goodsprings, as its members they talk of how they stick together to survive the unforgiving Mojave wasteland. This is an example of how back stories and context excite you into believing that the world is dynamic and alive, but this starts to wear off quickly once you get deeper into the game.
Characters do absolutely nothing outside their routine of moving from one place to another, usually to sleep in random beds. Cut and paste character animations and textures, under populated streets with non-named citizens who wear the exact same clothes (particularly in Vegas itself), predictable spawning enemies, tediously long and similar fetch quests, the list goes on.
The environments are one of the biggest let downs. Fallout 3's tightly designed environments are gone, replaced with large and empty expanses of land that take too long to move through, fast travel is also badly implemented and you'll still be spending too long getting to and from areas. If you've played Fallout 3, then these streets will also look familiar, because they are the same. The exact same textures, models, from the street lamps, to the fire hydrants. The exact same character models, perks, clothing, etc. The atmosphere also takes a beating as the dreary grey color scale from Fallout 3 is now lost, leaving you with a strange western color palette that does very little to set the tone. It also doesn't help that the exact same gameplay from Fallout 3 has been reused here, VATS and all. The new additions (some perks and a lot of new weapons) spice things up a bit, but it leaves the game looking like a very big expansion. This makes exploring the Mojave Wasteland less then compelling than it could be, because you feel like you've seen it all before. At this point the game stop immersing you, and begins to feel like a chore.
What keeps this game going is the main story line, everything else leaves little to be desired unless you can get over the issues mentioned above. This is because the main plot keeps the world alive, it does seem to change, and with your guidance. But with that only leaves a very short RPG experience that had so much ambition where it didn't count. I had a good enough time with Fallout New Vegas, but it wasn't as much fun as I would have wanted it to be. My character remains a low level, and I have no intention to return to the Mojave Wasteland.