Most of the characters are great characters, because they're the creations of a good writer. But most of them, I think, don't come across as people who would be particularly likeable IRL. It's not that you wouldn't like them if you met them IRL, thoug, it's just that we as readers know more about their faults than we know about the faults of our more casual friends. Our closer friends are different; we know a lot more about their faults and problems, but usually we become friends with someone before we know a lot about them (first impressions are important), and then when later we learn more about the negative parts of their personaliities, we aren't going to abandon them just because they aren't perfect.