Aight motherfuckers Veigar's gotten his little rework on PBE and while I'm not good at writing official shit I'll try to put in my own words
Firstly, his Q; far better now. Has a Lux Q effect in that it can pierce through a single enemy so he can grab 2 minions at once giving him some nice sexy increased farm. Range also appears better, and it's a skillshot now so you can actually pick off running scrubs that you can't see. Apparently the cooldown's lower at lower levels but not as low at higher levels so it's more consistent but less snowballish all game, a change that I don't mind at all considering that I love everything else about this.
W's claimed to have no changes but it appears a little faster to me, eh anyway
E's been arguably nerfed but IMO it's just a lot fairer now. The radius of the horizon is fucking gigantic so you can hit it from further away and it's better at catching multiple enemies now, which, combined with his piercing Q means Veig overall has some more multiple target options now if you play him right. It also means that, combined with his new Q range he can play a lot safer early game if he choses. The big thing is that there's a 0.75 second delay that means the enemy has a small window of time to react, but it's hilariously large now so it's easier to catch them with it if you predict their movement in advance, and still has that domineering presence even when it's not up so it's fairer to both sides and actually requires some skill now.
R apparently got an AP ratio nerf but the cooldown is lower like with his early-game Q so that means Veig's sacrificing a little bit of his humongous power to have some more consistent damage throughout the game, another change with I'm completely fine with.
Overall Veig definetely has a higher skillcap now (if not all that high still); play your cards right, you can kick ass left and right and possibly flip the birdie at old Veigar, though misplay also means less damage than old Veigy. He's more fair to both sides, is more interesting to face and has more options, reliability and consistency damage plus faster Q farming so now while it feels like R nerf makes him deal less he can probably scale up a LOT quicker, which is essentially the trade-off for DFG
of course I'm a shit player so we'll see if I can actually still be good at him like I was but I definetely think these changes are for the better and makes his game a whole lot more interesting