The world building is excellent.
Vegas, the supposedly biggest city in California is a place with rougly 10 people roaming in the void.
What did you want? that they spam hundreds of NPCs roaming in Vegas? i don't think the engine could handle that well, specially on consoles. You have to use your imagination, every city/town in RPGs are small compared to real life.
Also the "world" is just an empty theme park in the desert filled with empty boring locations all around the map.
It's a wasteland, post nuclear war world for a reason, why are you comparing it with the tropical island of FarCry?
All your complaints are empty:
Graphically, it's puke-inducing.
The graphics are fine for a 2010 game, it's brownness is justified as a wasteland post nuclear war game, and Fallout 1 and 2 are brown as hell too.
Gameplay-wise it's worse than any FPS in the genre. It's clunky, poorly-made and extremely badly designed and a complete disgrace for an FPS.
I disagree, i remember having fun killing enemies with sneak shot, from distance. I don't know what it's 'good gunplay', i do know what's bad gunplay, see Blood 2, and Fallout New Vegas is not near that bad. Lot of different weapons to use, melee is super fun, killing enemies is satisfying due to the gore. The only thing i did not like it's too costly to repair the good weapons, as far as i know there's a limit of how much money you can make in this game, one time i found a super minigun but it was too costly to use it, which would've been fine if there was a reliable way to make money.
The AI is in shambles, literally.
in what way? enemies getting stuck is to be expected, like in any open world game or game with complex geometry. There's more AI in Fallout New Vegas than the first two games: each npcs have schedules, house to sleep and you can hide from them after they detect you, NPCs in the first two games just stand still, their only individual AI is to walk in random directions sometimes. It's not fair to compare since it's a different engine, but there more "absent" AI in the first two Fallouts.
The Factions are all rushed and expediated, Caesar's Legion(supposedly the beast from the East is a bunch of 30 dudes in football uniforms fighting with bat in an universe with guns??????) is a joke, Boomers faction is a joke, The Khans Faction is a joke. Enclave is a joke. Omerta is a Joke. The Strip, the casino is a place with roughly 10 dudes roaming around in the void.
I don't remember the factions lore/motivations well, it has been a long time since i played it, but again your complaints about only a few dudes roaming around it's not a valid complaint. There's have to be a abstraction so that the engine can handle, here NCR population lore:
Since 2241, New California has been radically growing in size.
[18] Their growth has allowed the NCR to become the largest known post-War country, with a total population number above ~700,000 (excluding transients and people without citizenship) by 2241 (40 years before the events of
Fallout: New Vegas).
There's no way a game like Fallout New Vegas can handle a population that size, only few strategy/management games can handle a thousand 'NPCs' on the same screen, like the total war series, but the 'NPCs' in these games are less detailed, more abstract and have 'mob AI' instead of individual AI. Even 50 NPCs on the same screen would be too much for the bethesda engine, so it's to be expected only a few NPCs in the game. Caesar Legion army size is estimated to be 5.000 to 10.000 men. Fallout 1 and 2 does not have a lot of NPCs either, only a dozens in each location. Your complaint is empty and could be used against any game, even Daggerfall with its big towns filled with NPCs still small compared to real life towns.
invisible walls to spice it up
How is that a valid complaint? what did you expect? that the map would go on indefinitely? you have to be a massive bitch to be bothered by this.