I like the version of Shadowheart we have right now a lot, but I still think we have a very limited version of her right now, even when compared to other companions, because even she doesn't have full access to her memories. We don't even know how much of her memories are missing. For all we know, she doesn't even know her real name. This means there is a lot of potential here, but it also means it could go terribly wrong.
I do enjoy the bits we do get out of her right now, and I'm hoping it will pay off down the line