*The graphics engine is DirectX 9, while modern games are at least DX10, if not DX11. Obviously this was done because the XBOX 360 only supports DX9, and they didn't bother to spend any time upgrading the PC engine to DX11, or at least adding some DX11 effects to the existing engine (like the latest Stalker game).
*The user interface was created for controllers. Why is the #2 limited to ammo switching? Because it's a button on the controller. I can't press ESC to exit screens, like VATS or a dialog, because a controller has no ESC button.
The worst offender is the Pip-boy. It's mapped to 3 keys, F1-F3. Come on, there should be a key for each Pip-boy screen so I don't have to keep navigating the stupid thing in the middle of a battle. The "M" key should open the map, the "I" key should open my items screen, "L" for flashlight, etc etc. It reminds me of Oblivion. Hasn't Bethesda learned anything?
*The bugs are so obvious that anyone can see them after a couple hours of playing. Seems like they decided to do minimal PC testing and patch it later.
*The mouse in the game menu is jerky and too fast. With a controller you just hit up/down, so they had to add a mouse function in there somehow. There are mouse problems in other screens, like the workbench or Pip-boy. Also, alt-tabbing out of the game causes my mouse cursor to disappear completely.
I can go on, but you get the point. They clearly they took the lowest common denominator and stuck with it. Fallout New Vegas has the quality I'd expect from DLC or an expansion pack. I think this game was released to keep riding the Fallout 3 money train, with minimal expense and maximum profit.
I expect to see a price drop soon, followed by an announcement about Fallout 4 with hope we'll forget about New Vegas. You will NOT have my pre-order money for Fallout 4 until I read the reviews and forums