Veigar is fine.
Seeing a lot of Veigar complaints about his not so recent kit change and it needs to stop. Veigar is a great champion now, fun to play, not infuriatingly difficult to play against, somewhat difficult to do well with but still very strong. His Q has the obvious disadvantage of being able to miss or be blocked by tanks/minions, BUT it comes with the advantages of being able to farm twice as effectively, able to hit two enemy champions, and allowing him to farm and harass at the same time. I'd take it over a boring targeted nuke any day.
His W, they claim is unreliable and impossible to hit, but they fail to see its other uses. First of all, if you land a cage, even if they just wander around inside of it without getting stunned, you will hit the W. It's that easy. Second of all, it's an extremely effective zoning tool in lane. Simply cast it over the enemy caster minions as your minions are about to die, now they've got to make a choice, do they lose farm, take massive damage, or go around and risk getting hit by a Q? Either way, you're in control. It also makes for a great escape/kiting tool. Simply throw down that W and they'll try to avoid it, from there you can either /laugh and continue running away, or follow it up with a properly placed cage and a Q for the kill. Easy peasy.
Now, the cage. Some say it's now as impossible to land as the W, I disagree. I think it's one of the easiest skillshots in the game. Don't try to go for the stun every time, instead, go for the trap. Ideally you'll want to stun them, but keeping them in the same tiny little area is just as effective, it's just a little more dangerous for you if they've got range. Luckily your burst is quick, deadly, and you've built Zhonyas so any retaliation is futile. Besides, if you aim the W in the middle of the cage, it'll hit at any point of the cage, but the enemy often don't think of that and they panic when they see the little sparkles, running straight into the 2 second stun and still taking the massive damage of W despite their efforts.
TL;DR Veigar is fine. A little more difficult to play, but well worth the effort of learning him. If you can't handle the changes, perhaps you should try an easier champion.