Well, she is op into certain champions, and can be shit into others. She does have some early game mana issues if she has to spam her abilities to farm or set-up a few fights. But if she wastes her E, go in. She is really weak without it up. Her play style is similar to Kalista's so maybe that could help you in deciding how you want to counter her. And her E is easily dodged by walking to the side. Circle her in fights forcing her to fire her feathers in all directions. Basically, spread out her feathers and then none can really stun you.
As per meta shift, she is just facing more of her better match-ups. Caitlyn and Lucian were too champions who could easily contest her engages, sometimes even push her around. But with the Caitlyn and Lucian's nerf, they are no longer overly dominant as they were.
Is she strong, can be, especially with the right support backing her up.
Is she OP? Not really yet, but she has potential. Right now she seems balanced enough to where she has good and bad games. She can't always come back into games she gets behind in too. She can also snowball if allowed to.