I'm a zyra main. I play her mid and support and have nearly 800k mastery points with her. I've dealt with the changes to her kit that came with the mage update and with the nerfs over the course of the past year. This one is the one that has had the most impact and it's a little hard to swallow given Riot's promises not to force her into the support role and to keep her relevant in midlane (see the mage update threads for more on that).
Yet this most recent nerf to zyra's plant targeting has destroyed her power in mid lane. It's a good idea for zyra support, but in mid lane, her ability to trade and punish enemies who get too close is greatly diminished.
Zyra is an immobile mage and she's already a tough champ to play mid lane and win. But with the plant targeting nerf, she's lost her lvl 1-5 lane presence and even post 6, she still struggles to have the ap carry potential that she did pre-patch.