In fact, her female protagonists typically fall somewhere between "hard to like" and "detestable." And they are all completely compelling.
Summers has written four novels so far, and it's hard to pick a stand-out example. Cracked Up To Be and Some Girls Are are both stories of ex-"It Girls" who are cast out (or cast themselves out) after a tragedy, while Fall For Anything tells the story of a girl searching for clues about her father's mysterious suicide. Her latest novel, This Is Not A Test, is ostensibly about a zombie apocalypse, but in truth it's a story of what it means to survive, especially when you don't want to.
They are dark books, with dark characters and dark themes. And not "dark" in a stereotypical YA stalker-vampire-boyfriend way. They are gripping and heartbreaking and somewhat disturbing, with frightening insights into the human psyche, and everyone is unputdownable and impossible to forget.
Summers has one of the most amazing voices I've ever read. Read the first line of any of her books, and you're immediately sucked in. The characters seem real from their very first words, and you can't help sticking with them and even liking them, even as they wear their flaws out for anyone to see. These aren't "flawed" clumsy RomCom heroines. They are ex-bullies. They shove away people who care about them and say things they really shouldn't. They're impulsive, and they are scared to act, even when it matters. They're cynical and naive, desperate to hope for something and full of self-loathing. They're raw and painful. They are, in short, some of the most realistic protagonists I have ever read.
I don't think I could give any contemporary writer a stronger recommendation than Courtney Summers. She's not the choice for a light, fun read, but if you like your books gripping and your characters so real that it hurts, definitely check her out.