As for how "likable" she is, I've noticed that the forums seem to show "mixed" reviews of her personality, acting ability, and likability. While all the other "New Girls" seem to have a greater majority of negative posts, often referencing the wrong age, bad lighting, bad acting, inconsistent editing, etc...
To me, a mixed review is a good review, because it provides more for the fanbase to discuss. Whereas a bad review is just that - bad.
Also, there's enough intrigue surrounding her character that I see a lot of possibilities for character development. As always, The Creators will likely take baby-steps, analyze the viewer response, and create the show we want to see.
I just hope we all want to see the same thing...

That all being said, I don't think she could ever replace Bree, but I do see her being a fresh addition to the ever-thinning story line.