While it is true the plot can be described as "slow-paced", it is excusable, for the book takes place over a period of 24 hours. This gives the author the chance to expand on minute details of the day, giving you the sense that you ARE there, and every detail is absorbed. Granted, this does make for a slow read, but Fast makes up for that in characterization.
The main character, Adam Cooper, is a teenager--naturally rebellious and not the most respectful guy someone could meet. He and his father have a shaky relationship, and Adam's little brother, Levi, gets his share of verbal abuse as well. But come the redcoats and the battle of Lexington and Concord, Adam learns what it takes to be a man after his father is killed and he's shown quite harshly what reality is all about.
One highlight I'd have to make is the smokehouse scene. This takes place directly after the battle, and Adam has fled to a smokehouse to hide from the redcoats. He's alone and scared when Levi comes looking for him. Levi and the rest of the family have found their father's dead body, and Levi is in tears. Adam--the same Adam who called his brother names in the beginning of the story--takes the boy into his arms and comforts him. Character development has always been a major thing in books for me, and this I just adore--both characters learn to accept and love each other (and I can't help but say the whole thing is very, very cute).
In short, the book is slow-paced and hard to get through at some parts, but I adore it soley for the characters, which are well-developed and easy to relate to. I myself am 14, and I read this last year in 8th and simply adored it. Who says a teenager can't enjoy this book? =D
As for historical accuracy, it IS shaky, but the Lexington and Concord battle is not the main focus of the story. If I had to guess, I would say Howard Shore chose his setting as mere backup for his development of Adam in his boy-to-man journey.
I adore this book, especially Adam and Levi. If you're into character-driven books, this is for you.