It's funny; with everything Sprig's older sister does, and the way she acts, you could pretty much replace "sister" with "brother", or change Sprig into a boy, and you could easily get a story that boys could relate to perfectly. That's how universal this story's themes are. Sibling rivalry, jealousy, getting angry at friends, missing a parent, and the various little things that happen in the story, are something kids of both genders can understand and relate to.
Each chapter is short, but something interesting is always happening, so the book moves at a great pace. Most importantly, the dialog and characters are very true to life, which is always vital in making a "slice of life" story work. I remember having similar disputes with my older brother, with him acting superior, trying to show off to his friends at my expense, and so on, except we got along better than Sprig and Dakota do here. Still, just about everything that happens in this book, I could easily picture and totally relate to.
It's not just sibling issues, either, though they obviously play a large role in the story. There's other little things going on in Sprig's life, such as the interest an annoying boy takes in her best friend, and an upcoming party intended for older kids that Sprig is allowed to attend. There's also a few attempts to mix in some more serious issues, which I thought was a good idea. They're not expanded upon tremendously, but real life has its ups and downs, its light and heavy moments, and I think they were fit well into the story.
The present-tense narration is a little unexpected, and takes some getting used to, but I like it.
I'd recommend this book. It's not the Great American Novel by any means, but as a realistic yet light-hearted slice of life story, it's great for what it is.