I'd like to keep this short (it probably won't be). Zoe's changes for patch 8.1 are as follows:
* Delay before Sleep Trouble Bubble (E) trap is created increased from 0.6s to 0.8
I'm perfectly fine with this change. It isn't, in my opinion, a major alteration although the increase in delay is noticeable and may therefore give players more time to escape the range of her E trap.
* Delay before Portal Jump's (R) exit portal appears changed from 0.1s to 0s
Again, no qualms with this one. Facilitating a player's ability to track and respond to Zoe's movement seems fair.
* Spell Thief (W) no longer grants Hextech Gunblade shards from minions
I understand how instantly gaining a lot of lane pressure and even kill potential at levels 2 or 3 in the form of this shard can be quite unfair, especially since its occurrence is totally independent from anything that a player facing Zoe can do. There is no counterplay to a Zoe getting a lucky Gunblade drop. I agree it shouldn't be made available at earlier levels, however one possible change for both this shard and others would be to gate them according to W's level. Make it so that, for example, neither Teleport nor Gunblade can be dropped with only 1 point in W.
* Paddle Star (Q) only registers Zoe's position after she has emerged from the second portal of Portal Jump.
This is the change that I have had trouble dealing with. Summarily, it makes her feel less fluid which in turn makes using her kit, specifically her QQR combo, less enjoyable and even detrimental. Getting into detail, this change can potentially punish a Zoe player in a way that is devoid of any necessary influence from the enemy player. It doesn't have to do with outplays, with dodging or predicting, it simply has to do with strict, clunky timing. The cut-off time for which Portal Jump must be cast right after the recast of her Paddle Star is not intuitive. Although repeated attempts at the QQR combo in its current state will of course help Zoe players develop a better feel as to when they must cast their R to prevent Paddle Star from fizzling out, it doesn't change the fact that there is now a harsh and instantaneous transition from "Paddle star range is extended" to "Paddle star fizzles out" which makes performing this combo unreliable and prone to error/failure. This is especially true in more intense situations such as full on team fights, when it is arguably most important for you to able to consistently throw out your damage.
If the reasoning behind this change is to reduce the overall damage from the QQR combo that comes with its extended range, but not necessarily reduce the range itself, I would suggest reverting this change and instead reducing her base damage while increasing her ratios to prevent one-shots from occurring as early as they had previously to this patch. If the reasoning was to reduce both the damage and the range from which Zoe can perform her QQR combo, I can't imagine this change being reverted (chances are it won't be reverted regardless) which in my opinion, as well as that of other Zoe players I would imagine, makes Zoe feels much less fun to play. With the way in which the range calculation for Q works when using her R, it is entirely best to steer clear from the QQR combo due to its unreliability; deleting an element of Zoe's versatility in performing combos with her kit and therefore limiting her gameplay.
A lot of people argue that there is no counterplay to Zoe. You get hit by an E and you die. In the 8.1 patch notes themselves they argue that landing Zoe's skill shots depends more on the Zoe player's skill than that of the enemy player. I can't say I agree, as a Zoe player and having played against other Zoe's, I find that you have the ability to increase your odds of dodging her skill shots. Although her E has a decently fast missile speed, it is also compensated with a relatively small hitbox. Constant random movements by an enemy player makes this skill shot much harder to land. Proper vision prevents E's from fog of war. In the same way that a Zoe has the opportunity to severely punish you for getting hit by her E, an enemy player has the opportunity to punish a Zoe for missing her E (a Zoe with E on cool down is extremely vulnerable save for Flash). The same can be said in regards to dodging her Q (very fast missile speed, relatively small hitbox). Reducing the range at which the QQR combo can be cast in the form of its current change doesn't alter what an enemy player can do to dodge her skill shots, it merely reduces a Zoe player's arsenal by having essentially made one of her tools/combos simply not worth performing. This is anti-fun for the Zoe player.