Played a game as Veigar
I was laning against a Kassadin, so I guess it wasn't really a high pressure lane, but for the most part it was alright. The Q changes feel really nice, and the slight nerf on the ult was tolerable.
However, he could really use some love on Dark Matter. I would suggest reducing the delay to about half of what is is now. Something along the lines of a 0.75 second delay. Right now, it feels like its main purpose is to clear minions as a champion that has a 99% slow can dodge it. As I play Malzahar and Cho'gath, I am used to landing delayed abilities, but Veigar's feels like it is just too long.
Event Horizon could also some buffs. Something like Veigar (and allies???) gains a 30% movement speed buff when running towards Event Horizon.
Disclaimer: I did not play Veigar before the patch.