This is a companion to Telgemeier's wonderful Smile, in that it's also about her life. You could very easily read either book without ever having to read the other, but why would you want to do that? They're both great.
Sisters, naturally enough, is about Raina's relationship with her younger sister Amara, from Amara's birth through Raina's teens. Nobody can push your buttons like a younger sibling. Anyways. Raina does a great job with showing just how difficult the relationship between siblings can be, and she does it without sparing herself. Yes, Amara is often difficult in this book, but Raina is, too. True, Amara does come off a little better through most of the book, but this is filtered through her own memories. I'm sure it must have been very, very tempting to make herself look better.
This is definitely in Raina's signature style: cartoony, simple, expressive. I like it, it's clean, and it works for what she's doing here.