I tend to ban new champions for the first week or two so I don't have to see them every single game.
You know that kind of behaviour, is contributing to the balancing problems, do you?
Because...in doing so, you make sure Riot gets as little data from the initial release as possible. Without a large amount of data, they cannot and will not make balancing changes. So by the time you realise that you waste a ban on something you have no idea of how op/up it is, and have many games overrun by champions which you KNOW to be op, and start getting ban patterns back to normal, the champion is still unchanged.
And if THEN it turns out to be op, oh boy, then things get funny.
Because now you are caught between a rock and a hard place...ban the op champion, or the new champion, who couldve been nerfed by that point...one or the other will get through.
Similar problems occur on underpowered champions: Those remain up for a huge amount of time (Hello Bard) up to the point where they are essentially useless (Hello Bard again). And then, when the banning goes away, Rito panicbuffs them, and they suddenly dominate (HI BARD!) :D
As to her actual strength, I have no idea.
Shes a great duelist, who can deal very well with tanks and mobile targets. If she doesn't want to be disengaged, she won't be, she can chase almost indefinitely and circumvent pretty much every escape mechanism. As such, she is a natural choice for toplane.
Her weakness is being singled out in teamfights, as she is no tank, and pretty much useless up until the moment she dives in. She can not peel back in a fight, nor kite a more powerful enemy.
So in short, shes exactly what the toplane meta needs currently to shake off the "hurr durr me build tank items only" - meta of boredom.