Potential, so much of it. Unfortunately most of it went unnoticed because of the technical problems. I'm going to cut the chase and go straight to business.
I'm not totally against romanticising slavery, it can be done tastefully, in a Cinderella-ish way, or not-so-tastefully. More Than A Slave didn't go too much into the untasteful side of it and some parts could've been written in a better way. But the romanticising of slavery was not what bothered me the most here.
Problem Number 1: What big secret that no one would want to know?
I didn't find it. I have a few strong candidates for it, but none of them are clear and perfectly fitting to the role. And if the 'big revealing' was the one I am thinking, then why it was hyped so much beforehand.
Problem Number 2: The rhythm of the text.
This I found the most annoying thing. The book consisted mostly of short sentences and then there were long, too long, sentences that made you confused before the halfway through. The shorter sentences prohibited the story from flowing.
Problem Number 3: The Characters' incapability to develop or stay in the role
This was a huge minus. I didn't see any development in the characters except slight differences in their behaviour. Then there were the side-jumps: Jumping from their own character's 'normal' personality into something entirely else that was not even remotely related to their character.
Problem Number 4: Skipping from point of view to another and repeating of events.
Sometimes, in some stories, it works, having multiple point of views, I mean. In MTAS it shook the packet maybe a little too much. The reader wasn't left even with an ounce of mystery because everything was laid out. What made me cringe, was the repeating of the same event from another point of view, even if, in my opinion, it was totally unnecessary. It made the beginnings of chapters' drag and the reader frustrated.
So yeah, the actual idea had potential. What ended up on the paper, not so much.