I'd recommend you buy Fallout 3: Game of the Year because:
1. Physics are just as bad
2. A lot more buggy than FO3
3. Downgraded graphics
4. Terrible storyline, Fallout 3 has a MUCH better one.
5. Even though they have a lot more different voices for New Vegas it still feels like I'm talking to a wall (this is exactly the same on FO3).
6. The iron sights is an improvement but the accuracy is pretty bad that it'll make you switch to third person in the end.
7. You'd think to keep people hooked on the game that you'd make the game endless, instead I actually finished the storyline without realising and now I cannot continue.
8. In my opinion, the side quests are better than the primary quests but that's what it was like with Fallout 3 to be fair.
All in all, I don't recommend this game and just buy Fallout 3 GOTY, Bethesda does not deserve the money for this unfinished game, even Fallout 3 is buggy too. No doubt they'll stick to the same engine for Skyrim which is unfortunate because I was going to buy that game, goodbye Bethesda and Obsidian but this will be the last game I am buying from you, what ever happened to almost-bug-less-Oblivion? I don't know and I don't care.