My theory is, you weren't properly introduced. True, not everyone will like a realistic, flawed character because not everyone will like a real person that rubs them the wrong way, but I'm sticking to my theory. Characters can be likeable with the right introduction.
How does an writer/author properly introduce a character? While I don't claim to be an expert on character development, this question has been heavy on my mind as I work through second draft edits of TWOI. Louisa isn't exactly an easy character to sell. The following are a few ideas I have :-)
Wait. Before I start my list, make sure you like your character. If he/she is your own flaws personified, everyone else is going to hate them too.
1) Give the reader a reason to pity, admire, or identify with your character. If you can manage all three, more power to you. Make their deepest fears and the desires that drive them clear from the beginning.
2) If their goal might seem stupid to the reader, answer the "why" question. The sooner, the better. And make sure the reason isn't stupid too.
3) If they have annoying flaws, show why they have them, and hold the backstory. For example, my character Louisa is a bit reckless and obsessive, but I'm making an effort to show the trauma and insecurities that sparked those traits.
4) Present them in their everyday world -- what they know, what they're used to. If your book opens with action, try to show them in their element after the action dies down. Preferences, quirks, likes and dislikes come to life in this kind of setting.