Great art, great characters, awesome enjoyment level, and overall score is 10.
The only thing that has a 9 in my almost-perfect review, is story. For some people (unlike me) it's easy to get the story the first time you read it. For some (like me) it's hard and you need to think long and hard about it before it starts making sense. Plus with the chapters coming out once a month, your brain forgets.
However, it is DELIGHTFUL. You can't see anything wrong with Pandora Hearts. It tugs at your heartstrings, it makes everything so...so depressed when you think about the events occurring on Oz and his companions. Without spoiling much, let me say this one thing.
You will NOT regret reading it, because it would be the best choice of your manga -reading life.