Taliyah feels disappointing to play (Worked Ground)
The main issue with Taliyah is worked ground. It's pretty frustrating that you create these zones all over your lane, which do nothing but nerf the damage on your primary damage spell. The mana return and slight move speed boost aren't worth it.
It's also counter-intuitive to have to keep track of areas you've cast your primary damage spell, so that you can use it effectively. It's disappointing when you miss a kill, because you debuffed yourself by standing on working ground, which after about 3 minutes is probably covering most of your working lane space.
The mana returns and slight move speed buff are so weak, that I propose letting Taliyah have 5 rocks on every Q. The nerf to that spell that you get for having casted it previously just isn't needed.