Mischa was actually very good when the writing was strong and supported her well. I'm talking in the first season, before she became the media It Girl...already by the second season she was visibly less invested in everything. It was like you could see that she already felt like she should be moving on to bigger things and was halfassing it. She then became horrible. Remember that screaming fit she had in the second season premiere? That's embarrassingly bad acting. I hated most of the work she did after that...so imagine my surprise when I bought the first season and saw that she was really great in the early eps. She especially stole several of the first ten hours from everyone else in the cast. When she commits, she delivers.
Back then she was also incredibly gorgeous, and that didn't hurt either. These days she's meh and she's only acting in crap movies. And she seems like a bitch IRL (which is what a lot of people say too).