On a scale of 1 to Simbro how broken?
Hmm... It's playable, it just gets messed with some dialogues, or choices, etc. Eg: the game will act as if you had every single sexual encounter, so when talking with some NPCs they will comment or act as if you had every sex scene because they and your protag will talk as if it had happened. Or sometimes will bring up companions that you might not have even met, etc. There's more, like Gallery sometimes crashing, Quests not showing up on journal after a certain number of them, etc.
But again, it is playable, just annoying when you start running on the bugs. And it only increases as you reach the latest acts.
I think the only thing I never had an issue with bugs was combat tbh.