I haven't heard enough of her stuff to make an educated decision, but what I have heard has been enjoyable enough. But that's not a result of her singing abilities. And I don't know how much she contributes to the writing of her music. So I don't know how much, or how little, to give her credit for.
Her persona is a bit off-putting, but not nearly as much as other artists. I do think it is a shame that any story I read/see about her is about her though, and not her music.
* edit: just did a little reading and it looks like she writes most of her songs, with collaborators, so I'll give her more credit for writing enjoyable songs.