My rating system is as follows:
I can't even finish this book!
I can finish the book but it takes some serious effort.
I can finish the book but it feels like something I have to read instead of something I want to read.
The book is okay but not something I will recommend to my friends.
I really liked the book and will recommend it to my friends but it's not something I will read over and over again.
I couldn't put the book down it was so good! I will recommend it to my friends and will probably re-read it again in the future.