She suffers from a lot of the same problems that Yi does. A Yi will completely wreck your team if you have less than 2 CC and no one is running exhaust, anymore than that and he is completely shut down in team fights. Her ult being a free hourglass with lifesteal component is nice, and she is very strong. I've won pretty much every 1v1 lane match up top with her, but she suffers come team fights.

Her damage is strong, but it's mostly sustain damage rather than instant burst. Unless ridiculously fed, a smart team with proper CC can shut her down really hard. In fact, Olaf is much better than her as a solo top or jungle pick in every way thanks to his new buffs.