I can't even count how many times I've heard people say 'I don't have to like the characters to like the book'. I'm just the opposite. How much I like a character - especially the main character - is tied directly to how much I like a book.
Now, this don't mean that I need all my characters to be 'classically likable' (sweet, kind, thoughtful, compassionate, considerate). In fact, if a character is too much like that - or, sometimes, like that at all - I'll probably hate them. But, just because my favorite characters in the stories are…problematic, that doesn't negate the fact that they are my favorites.
I remember once saying (about a TV show) that 'if I like the people enough, I can sit there and watch them eat and be happy'. Books are no different for me. Have a good dinner conversation, and I can easily enjoy myself.
I can forgive - or sometimes not even notice - plotholes if I like the characters. I can forgive a weak plotline if I like the characters. (Of course, the best books don't suffer from this even with amazing people.)
Characters can basically make or break a book for me. When I like the characters, I can get invested in the story in a way that I can't when I don't like them.
This is the main reason that I tend to shy away and not have the best luck with first person narrated books and ones with only one main character - because all the attention is on them and if I can't like them - at least a little - I really struggle to enjoy the story. And, if I'm being totally truthful, my least favorite character is quite often the main character.
How about you? Are you one of those that doesn't need to like the characters to like the story? (If so, I'd love to know what makes you like the story.) Or are you like me and pretty much have to like the characters to like the story? (In that case, unite.)