I liked her in season 7, but in season 5 she really is too whiney imo. I know she has a tough life but that's no reason to behave like a 6-year old girl. Seriously, that's the last thing 14-year old girls want, they want to behave all grown up, and apart from Dawn wanting to go patrolling with Buffy, she's just too immature sometimes.
But there's something else what bothers me (and probably also her, if she were real that is ^^): I hate i how everyone treats her like a little girl, which she (even though she behaves like one) is not. I mean, she's 14, 15 years old and they don't tell her her mum has a braintumor? (They did, but way later if I recall correctly: Buffy knew it in the beginning of the episode and they told Dawn in the end, or something like that) And Riley telling her everything is fine, while it clearly is not ( he also knew Joyce had a tumor when he said it). And the way Buffy explains her why Joyce has mood swings etc (The tumor in her brain makes her say silly things) I can understand they don't tell her aboout being the Key. But concerning Joyce they really treat her like she's 10.14 year olds can deal with things like that, but they cannot if no one tells them about it in the first place. No wonder she behaves like she does, I almost feel sorry for her. 😛