Personally, multiple endings are okay but usually the execution in games is not that good. If CG is locked behind different pathes, and especially when the playthrough of the game takes 10h, then I usually don't want to replay it 6 times for 6 different endings, even when the replaying won't take that much time because I already know most dialogues and can skip them. I think that's usually the biggest issue: The re-using of the initial dialogues and stuff. The stories usually don't vary enough to replay.
An example for a good plot twist would be: Example initial base route: You go for Partner A.
But if you go for Partner B: Partner A will get jealous and totally change her behaviour towards you.
--> This makes it feel like two different pathes are worth it, since the plot itself changes and relationships between persons also change.
But usually it is executed like this: Base route: you go for Partner A.
But if you go for Partner B: Your relationship with Partner A and 90% of all Dialogues are the same, but with Partner A you just will never progress to sex.
--> In this case, everything stays the same. Just the progress with Partner A is on-hold and you can't progress further and are stuck with basic interactions with Partner A, and the same basic dialogues - while you progress with Partner B.
And the worst of executions I once saw: You can progress with all Partners. But depending on how much/less you progressed with certain partners, you will get different endings.
---> These kind of games made it feel like a riddle. You had to try different combinations of relationship progressions to see, if you will get a different ending or not.