I'm THRILLED that KB is joining the cast of Heroes, even though it's just temporary. I'm a huge fan of hers from Veronica Mars and I think she's incredibly talented. I'm happy to see her working again - and happy it's on a show I already like.
I've seen some negative reaction to her casting, saying that the show doesn't need another blonde ambigously moral character. But I think KB's acting is what people should focus on.