I haven't read the first in this series, but I wouldn't mind going back and doing so now. Despite not having met any characters yet, I did not feel as if I needed book one to get connected. Lisa Ard does a nice job of reintroducing the characters to a 'new' reader. It didn't seem too heavy, either, that if you had read book one you would be annoyed by it.
That being said, I really enjoyed the characters. The relationship between them felt true to how relationships work in real life, so it was easy to believe. His sister is available and willing to help him, but also reflects the fickleness of sibling love at that age after she helps him. I loved that. I really liked the realistic portrayal of Patrick going through the voice change, too. He was embarassed and felt that his world was crashing down. At that age, any hiccup in life makes you feel that way. Even as adults that happens.
I also enjoyed the historical theme of well-known baseball players, who help Patrick realize that there are worse things in life than his changing voice. I think everyone, from kids to adults, need reminding of that. I didn't feel the story was bogged down at all by any historical facts, which is really good for the age range the book is aimed toward.
The one thing that distracted me from the book were the pictures. I realize that's a small thing and not a reflection on the story itself, but the pictures tended to take me out of the story a little every time. Another thing I struggled with at first is as an adult reading it, I noticed the message of following your dreams and not to sweat the little things in life very quickly and at first felt it was laid on a little thick. By the end I didn't feel that as much, and I imagine a kid reading it would barely notice it. That being said I could definitely see myself reading this with my son when he gets a bit older.