So, the only real issue with new Poppy..
Personally, I think she's great. She's fun, hilarious, and makes for some very interesting gameplay.
Howeverrrrr, I feel like her ultimate is... Eh. I mean, don't get me wrong, there's something great about knocking someone into the jungle/base, but when you're standing in lane, that's not what you want to do with it (especially because it's damage is so low). The chances of you killing someone with it under tower (Or even hitting them with it) are pretty low. But the worst part about it? The fact that they're 100% invulnerable while in the air. This includes both the minor knockup and the huge knock-back. Honestly, I feel like with the huge knockback, sure, make them invulnerable. But the knock-up feels TERRIBLE making them invulnerable. You want to use your ult for CC, but instead it's used and your allies miss all of their important skills because they're 100% immune to damage. This helps the enemy team more than hinders them; It's just as bad as hitting your own team with a Bard ultimate. It can cost your team a Ziggs ult, a Brand ult, and the list can only go on from there.
Could we please change that? I feel like Poppy's in a great spot in terms of balance, but that ultimate just feels terrible to use, especially when it hurt your team.