The War at Ellsmere is not exactly a groundbreaking graphic novel. The story is instantly familiar: a scholarship student at a ritzy school runs up against a snotty mean girl. There are any number of school stories built on this same framework, and Hicks doesn't do anything spectacularly novel with the plotline. We know from very early on how this will go, even if we don't know the specifics, and we aren't disappointed.
Where Ellsmere really excels is in the characters it builds. The girls in this book, including our protagonist and her slightly spacey friend, act and react like real girls. And, believe it or not, so does the bullying antagonist. Hicks does a great job of showing why Emily would be so set on maintaining status quo without going into preachy mode, and without giving her a too-good-to-be-true ending. I also appreciate that she doesn't try to paint Emily as the mean popular girl. I suppose those girls must exist, but my experience in school was that popular girls were popular because they were so well-liked, not because they were adept bullies, and that mean girls weren't popular outside their small cliques because they weren't likeable. That seems to be exactly what's going on with Emily, and I like that Hicks didn't fall into the popular=mean cliche.
That said, the ending brings in a strange mystical element that's completely absent for the rest of the book. I can go with it, but it came out of nowhere and wasn't even necessary. The plot was getting resolved on its own, thank you, and didn't need a dose of magic. It came out of nowhere, and I think the book would have been better, or at least no worse off, without.
Of course, I love Hicks's art. She's so good at giving her characters real expressions and distinct looks. Pair it with the writing, and the characters in her books become real people, even with her somewhat cartoony style.
So no, there's nothing strikingly original about this school story. It's just remarkably well done, with great art.