One of the girls in book club did say she didn't like the format because it's written like a journal. So, if you didn't catch it from the title, this is in diary format. In case diary/journal style writing isn't up your alley. :) I like reading books written in this style. It makes it seem more personal; like you're getting to see everything- the good, the bad and the ugly. And even though Sarah's time was way before my own, I feel a connection with her when she describes her happiness, her dreams, her rebellious thoughts and even her grief.
There are parts in the book that will make you laugh and parts that will make you cry. I think the combination of the two make for a great book.