The visuals and mechanics are basically all the QoL improvements you could ever want from FO4. There is a mass of story and lore to work through.
Don't worry about having the perfect equipment loadout, you'll see a thousand youtube videos telling you what the best legendary versions of each item is and how you need to have that particular model to be effective in a fight.
But they're wrong, i watch ManyaTrueNerd do most of his playthrough with a stock pipe revolver and RyconRoleplays did a permadeath run using a bow. All weapons are viable if you have the right perks loaded.
The perk cards? It's a great system. Do you remember how in FO4 after around level 25-30 you were nearly unkillable and a master in every type of combat? 76 stops this power creep by limiting you to only 50 active perks, max out your single shot sniper and shotgun damage perk, sure, but now you'll be meh with automatic rifles, heavy weapons and pistols.
It's not a "real" MMO, it's more like a single player game with optional co-op. You don't need to play with other people, in fact if you don't visit their camps or join them at group events you probably won't see another player.