Spoilers for Curie's storyline follow. Avoid if you have not done this storyline.
Okay. Warning done. So, having switched Curie from her Mr Handy body into that of a Synth, I am seeing one particularly obvious problem.
Regardless of what you might equip to her, or her default weapon (she'll draw a laser pistol if you ready your own gun) might be, when you enter combat she will put it away and start punching targets instead.
I'm going to assume this has something to do with her AI logic of her previous body being applied to the new one.
It's utterly broken, to semi-amusing effect.
You can't really use her as a companion until this is fixed. She has zero range of attack.