It feels like she lost a lot of power, and gained very little in return.
P: Old passive was powerful, no doubt. New passive has
blob level counterplay and doesn't seem to do very much unless you use it to last hit minions. Unless the numbers on her damage and shielding are high, this is definitely a step down.
Q: Old Q was damn powerful. %HP damage, magic damage burst on an AD kit made for excellent amounts of mixed damage, and it was an auto attack so it almost couldn't miss if you were in range. New Q is like a mini
Q, not the easiest thing in the world to land. About the only good part is that it gives her some form of waveclear without needing to build an item for it, but that damage better be freaking outrageous or else this is also a step down.
W: Old W was effective, but boring. Lots of invisible power. New W still has lots of invisible power (which is bad), but also has a component that stops most forms of mobility. Definitely a step up from the old W, since now you can't run from Poppy, or catch up to her.
E: Stayed the same, which is both good and bad. It's very situational as to whether or not you get a stun, and Poppy can very easily be knocked out of her tackle by just about anything. It seems to have one of the lowest priorities in the game (to borrow a fighting game term). Maybe they fixed that, but it was probably a copy/paste job. That tackle should be reliable, since it doubles as her stun and her gapcloser. Old E was not reliable.
R: Old ult was so powerful it nearly broke the game. New ult seems horrible. Poppy doesn't want to knock you away, shes wants to keep you nice and close so she can beat your face in with a giant hammer. And always knocking toward the enemy base? Jesus Tittyfucking Christ that's stupid. At least let Poppy knock people under her towers. This seems like a huge step down in power from her old kit.
So if we tally it up, she lost loads of power on her passive, Q, and ult while gaining a bit on her W. That's not a good trade at all. Poppy's numbers better be really high, or this rework is actually significantly less powerful than her old kit.
Then again, her old kit was "Go in, kill bitches, give zero fucks". This new kit is "Gotta protect everyone". Such a screamingly different playstyle. Not saying the idea of defensive tank is bad
but it's not Poppy. Poppy is offensive. This new creature is someone else that also just happens to be named Poppy. Someone less interesting as a whole. If I had the power to veto this rework, my finger would be bleeding from pressing the button so hard.