I am kinda disapoint with veigar changes...
Now dont get me wrong, the changes to the Q are godly and i love it, but the E change for me is hit or miss. Sure its harder to hit but im sure it will get easier over time...
but none of this is what is bothering me
i feel like his iconic ability (his ult) could have so much more.
but first what makes a mage top tier?
Burst -
CC -
AoE -
Mobility -
alot of mages have 3 of any combination... and some have all 4 >.> 
veigar is sitting the line between a viable pick... and a non viable one. And honestly the only thing keeping him from shining is the fact he is so single target focused.
i could ramble on about what could or should be done but i feel like balance wise and thematically his ult would have been cool if after you use it, it leaves behind a destorted zone that slows or even does DoT. It would just fit imo. IDK im gunna do some more play time with him on pbe but i hope riot doesnt leave him for another project