Will be completely honest and say I haven't tried the rework myself yet, though here's what I think of it so far:
Passive: Glad they got rid of the previous one. Havn't seen the numbers on the movement speed yet, although will probably be an OK ability.
Q: Really glad they didnt touch any of its mechanics (still circular delayed ability with movement speed increase)
W: Will probably make her gameplay against mobile champions somewhat easier. Will be so much fun counterplay in this :)
E: TLDR version: Dont like. Miss the reset mechanic. 1s will make her feel slow early game (0.55s with 45% CDR, which will feel like the old one.) Balance issues.
Long version:
I actually REALLY dont like the changes they did to this ability, primarily due to balance and difficulty concerns (I liked the harsh punishment for missing poisons). Here's why I'm afraid of her future balancing: As it's supposed to be now, you get a flat 1s CD on her E, with increased dmg if the target is poisoned. Now this can be balanced by giving the ability low dmg if the target isn't poisoned, and OK damage if poisoned.
Now what if I decide to buy Rylai's? You would pretty much be able to start of by casting 1 E to trigger the slow, follow up by her poisons (which are really hard to avoid because of the slow), and then you just continue with the "old combo". Now my question is how are you supposed to balance this? I'm afraid she'll either end up being completely overpowered (and thereby permabanned), or completely useless because they have to balance around this.
I also feel like the changes reduces the difference between a good Cassio player and a crap one by a huge amount (High skill ceiling pretty much removed)
R: Unchanged as far as I can tell. Quite happy it stayed the way it is.
Overall: Don't like changes to E. I think it makes her way to easy to play, and removes her completely from the "hard champion pool". Also may create balance issues. Quite happy with the rest of her kit (although, for me, the E changes overshadow the rest of her kit's changes).