As many people have said, the writing style of this book is tough to get past and probably means that many people will be put off reading what ends up being a cracking story. The author has obviously used the style and structure of the Jerilderie Letter as the jumping off point and imagined Ned's voice using that tone throughout the book.
If, like me, you have never heard of the Jerilderie Letter before considering this book, it was the famous letter that Ned wrote with Joe Byrne documenting some of his history and the injustices that were suffered by people of Victoria at the time.
The style of the letter (and, it was argued, the education level of the writers) meant that everything tends to run together. There no speech marks, hardly any commas and very long sentences. For example, "Mrs. McCormack gave good substantial evidence as she is well acquainted with that place called Tasmania, better known as the Dervon or Van Diemens Land, and McCormack being a Policeman over the convicts and women being scarce released from that land of bondage and tyranny". Phew!
Peter Carey has used that exact writing style to give voice to Ned's life, starting as a very young boy and running through to his last standoff with the police at Glenrowan. This is very impressive, technically, but not easy to read. There are many sentences and paragraphs I had to read more than once to get a proper idea what was going on, or who had been speaking. Carey also invents a lover and daughter that Ned is writing to in order to provide a structure and reason for this comprehensive history to be documented. I imagine purists and historians may take issue with this.
I came to the story knowing very little about Ned Kelly other than the fact that had a stand off with the police wearing a homemade suit of armour. I knew nothing of the struggles and trials of life that the poor people of Australia dealt with at the time, although this book has made me research that further since. It gives you a good sense of the time period and the people involved, although the view of injustice and police involvement is obviously written from the point of view of the victims so does not represent a truly objective view of the time period. Still, the book sets out to describe things through Kelly's eyes, so you couldn't expect it to be an unbiased history lesson. It certainly provides more colour and interest to read it in this style.
Overall, as others have said, try the first few pages and see how you get on. If you can get past the first chapter, I think you'll keep on reading. I am very glad I did.