Alright, I was a big Veigar player through season 2/3, he was one of my first mains. Figured I should weigh in on the changes, since everyone else seems to be.
First off, I love his Q. LOVE it. Sure it's a bit less of a faceroll to harass in lane, but it adds a tremendous strategic element to its use, and is much more engaging to play against. Plus, there's just just so many satisfying bonuses; killing two minions with it, hitting an enemy champ behind a minion, hitting two champs that are getting bursted by W... couldn't be happier with that change.
In contrast, his E needs some major work before it goes out. I see what Riot was going for with it, trying to make it more of a trap to limit movement than a guaranteed stun, but his W is nearly impossible to hit without cc or leading a chasing target. The way his kit works now, he NEEDS some form of reliable cc to hit his W, and without it, he has nearly 0 kill potential without getting a gank in lane.
I don't really have much for suggestions. The delay could be shortened to .5 seconds (it's huge right now), and something should either be done to give him more reliable cc, or to reduce his reliance on his stun. Maybe adding a slow that's strongest in the center, giving him more choices with the use of his cage? ("I can either risk them getting out and try to land the stun, or just go for the safe slow") Either something like that, or widening his W radius/reducing the landing time, because he's really not in a viable state currently.
Thanks for taking the time to read, would love to hear any thoughts/counter arguments.