I haven't been able to read it yet, but apparently, the main character is black. It is one of the few truths the protagonist, a compulsive liar, admits to.
The fact that a white girl appears on the US cover has caused further trust issues with the way the character is perceived as well as expresses a tendency to assume "whiteness" is more marketable.
Justine Larbalestier wrote her own well-crafted and insightful blog post in response to all the dramas. You can check out what she had to say here.