I was pleasantly surprised by Invisible. I really enjoyed it. I wasn't expecting it to tackle a lot of the issues that were addressed. I have a little issue that I think could have been addressed earlier in the book: The setting was unclear. From the language, I assumed the book was set in the U.K. but about half way in Sydney was mentioned and I had one of those "Wait a second..." moments. It's set in Australia! Also, it muddled my feelings toward the characters when I found out they were only twelve/thirteen. They seemed a lot more mature.
As a result, I don't feel I can give it four stars, even thought I want to. It is a great read, so don't take my three stars as a bad criticism. When I got it, it was a Kindle Freebie, and it more than met my expectations, and if I'm honest, it is better than some books I have paid money for.