Fallout 1 and 2 are more similar to each other than anything else out there and if you disagree you're a fucking YOUNGSTER who hasn't played, watched or seen anything. The plot holds up well but the plot is genre slop in both of them and if you disagree you're a fucking temporally challenged YOUNGSTER who judges Fallout as if every game in the series came out in 2025.
The most dated things are the stats and combat. APs and crits are everything, stack APs, stack crits, hit the eyes, pick a sniper rifle, get Ian/Sulik, hit the eyes and you're golden. There isn't any thought involved once you realize how it works. At least melee is kinda fun compared to some spiritual successor shit like ATOM RPG.
The companion roster is great and is arguably one of the best things about the games. The quests are fun. The graphics/audio design is great. Temple of Trials thingy is overblown because you don't have to fight anyone there. I'd say it holds up very well still. If you like the idea, go for it. If you really liked it, check out the mods. Get Restoration Project, it doesn't add anything that'd ruin your first playthrough.