granted, i basically Just did the main quest, like i do with pretty much every game when i play it for the first time. also, i'm playing ttw so i can't comment on the mechanics. it's just new vegas.
anyway i think my main issues are the pacing and the lack of agency for the player character. i actually like karma. i think it's a little reductive -- like the best rpg quests are always going to be ones where you have to pick the least bad option or the right answer genuinely depends on your personal politics and morality. but i thought the way people would come up to me in megaton to thank me for being so helpful, or the way three dog would talk about how much he loved my contribution to the good fight was fun. i don't want bethesda to bring it back, but it's fun.
i also liked that i ran across a couple of alternate ways to do things. nothing big. but like the vault 87, the way that helping/recruit fawkes is optional and you DO have the option to play someone who would not trust a super mutant. or when he tells you to trigger the release for all the cells, if you have a high enough science skill you can hack the terminal and release him. these are the most basic ass alternate options but later bethesda games kind of lack them.
i liked that there were skill checks. i know todd did away with individual skills in 4 (which i honestly don't care about) but playing a high int lw was fun because i got to make friends with smart people by being smart to them. the high int options were hilariously never really great leaps of logic imo but. hey. they tried.
anyway. the pacing: the first half of the game, where you're trying to find your dad, is pretty okay. this is also coincidentally the part of the game where the player has agency. kicked out of the vault, they go "well i need to go find my dad" and they decide to undertake actions to further that goal. once you get involved with project purity... i don't know. i was waiting for someone to emphasize the, like, "you're inheriting your dad's work, the thing he sacrificed himself for, you're becoming his mirror" or what ever. which maybe didn't need to be said, but bethesda games are not known for being light-handed with these kinds of things. it just never felt like it was my character's choice to continue with project purity but just what everyone around them was telling them to do.
the last couple of quests are also SO rushed. like you probably spend quite a bit of time on your own trying to get the geck. i did. getting TO little lamplight, getting TO paradise falls, dealing with that whole thing, then getting BACK to little lamplight, going through the whole vault. that sequence was ~2.5 game sessions to me (mostly because i got distracted doing the quest in arefu BUT STILL).
and then once you get out of raven rock, the geck is forgotten. i mean i think elder lyons asks you about it and you just go "yeah the enclave has it" and he goes "okay well here's liberty prime" and you go "wait who" because like yeah he's been there the whole time but no one ever TALKS about him. in fallout 4 they 1) give you their clear reasoning for bringing and rebuilding him and 2) have you HELP rebuild him in multiple ways and 3) the march to the institute is SO much longer than the march to jefferson memorial. anyway, and then that's it. the purifier is magically working but its an EMERGENCY and someone has to die about it. and then the sort-of antagonist is there and he dies in one hit and then the games over. hooray.
also im sorry president eden tells you that he wants to genocide everyone and then ALSO tells you that colonel autumn thinks he's too extreme. so exactly why are we so opposed to the enclave having control of the purifier. it literally purifies All The Water it isn't like they can keep it from the wasteland.
like no one would ever accuse emil of being a good writer but the main quest of 3 is just atrocious.
at no point was i, like, BORED or frustrated. so it fulfills the basic requirement that a video game be Fun. but it's like a 6/10 game and i maintain my assertion that anyone who claims fallout 3 is one of the best fallout games or even, GENUINELY, that fallout 3 is better than 4 is blinded by nostalgia because it simply isn't.