I just came back from a 3 months pause and saw they reworked the champion. I immediately tested 
and was really disapointed with the change. I used to max my "Q" first for wave clear and pressure and its just impossible now because of the nerfed AP ratio from 0.9 -> 0.55ish. Now cassiopeia need to max "E" in order to be effective but it is counterproductive with her new passive requiring her to farm.
Short answer: YES!
Ever since her nerfs ("rework") she has been rather trash.
Honestly, I liked the news about how they were fixing up E since there were some pretty whacky bugs when I played her. I almost always maxed E for Cass pre-work and only maxed Q when I was against a hard lane that I would need to just farm in. That being said...
They shouldn't have based her ENTIRETY off of her Twin Fangs. It was always about her Q and hitting it and poisoning then E-rush. You were rewarded for hitting the Q because it actually hurt and it would hurt more if you followed up with E. Now people just eat those Qs like whatever. Yeah, sure, you can spam E faster and much more, but since her passive has now been replaced with some crappy stacking passive (like wtf, of all the things, why that?), you can't even spam E as much.
Overall, yeah. Cass rework was a mess.
"hey let's come out with a new splash for a champion that hasn't been seeing a whole lot of play lately but has had a pretty dedicated base of players who like her playstyle, tie her into the new lore that we're trying to shove down players throats, THEN lets "rework" her (hehe you know what I mean guys) right into the ground!" - Riot bukkakeing Cass with all of there design teams
you max e and it refunds your mana cass can farm 24/7 and still have full mana bar
but yes she is underperforming because her power is gated for a long time and still its quite medicore
compared to the rework release when she had a bug on her E reset she's AMAZING of course compared to the patch before that (or really any other metric) she's still total trash.
The rework made it impossible to balance her, despite claims that it would make it easier. So her early game is in need of help, but they cannot fix it without making her late game completely broken.
Yeah, it's been rocky, to say the least.
The major problem is that Cass players are basically divided into two groups: those that like poison DOT and those that like E-spam. There seemed to be very, very few people that like both. The rework was supposed to move more into E-spam, but it backfired with a fairly convoluted passive.
Personally, I would have completely scrapped her and tried to deliver to both worlds by making Twin Fang add venom stacks to enemy champions, and go from there. Snakes aren't supposed to be using poison anyway.
The ratio on Q is actually even worse, it's at 0.45 currently. But you're certainly not the only one who's dissatisfied with this rework, there are plenty more threads like yours. Why not simply join our cause to get some answers from Riot?
She's pretty bad off currently. If you can make it through her atrocious early game you might be able to be relevant. Otherwise, she just falls (and stays) behind.
You farm by poisoning minions and spamming the living shit out of her e all day. it restores health and mana eventually as you last hit with it to rank her passive... inter and interesting concept. the problem i have with here now is that there is a ton of counterplay to an already very difficult champion to master.
Actually her rework was the only reason why I tried her at all. Newer played her before, but I liked how much damage I could do with her E. However I remember from her rework how annoying her poison was, you got hit with a Q or stepped in a W and it just drained so mutch health from you it was disgusting. I think the rework was trying to remove that annoying lanebully feeling from a lategame champ.
They basically shifted power from her dots to her E, also making her early game weak and making her a monster late game. A lot of people weren't happy with this, but I personally like the direction they are trying to go. She's a hyper carry now, which I'm ok with, and her potential damage is astounding if you can get all her passive stacks. The problem is I think they made her max stacks a little too hard to achieve, so she hits her power spike waaaay too late, if at all.
I feel the AP ratio on Q could be buffed, maybe not back to 0.9, but certainly higher, as it can benefit more from her passive and items as the game goes on. Also, I preferred the way they gave Cass AP for each stack, giving benchmark stacks more boost (she gets E spellvamp for example at a certain amount of stacks). They changed this during her stay on PBE (she now only gets the benchmark bonuses, no continuously stacking AP to continue to ramp up power) and as a result her passive became lack-luster, especially considering it was awesome before.
Basically, Cass was changed to be a late-game hyper carry relying on passive stacks and E, but there is still work to be done before she feels good.
