I love the new ability effects. I just think that he's been around long enough to deserve a full VU and maybe a new VO since it's pretty archaic. I know you don't like doing visual updates unless you're doing a gameplay update too, but Veigar got that a while ago. Since you're doing half of it, you might as well make Veigar's model and ability icons gorgeous too!
Alas, Veigar rests in that horrifying limbo of functional gameplay, but woefully outdated appearance. Riot has expressed an interest in updates to visuals only, but couldn't justify the time and resources they would require. Ezreal's update will test the veracity of their presumption, and if it goes well that success could open the way to similar updates.
I'd prefer to see his face more clearly under the hat and give him less of a hop to his walk.
Seeing a seemingly-innocuous yordle that you know is evil and power-hungry to the core would really help flesh them out as a fictional race. Yordles are still in the "planet of the hats" side of fantasy along with Noxians.
Of course, Final Boss Veigar would be best remaining like it is and very little, if any, changes.
