People think that veigar is not good but if you play against him you would realize that he is annoying.

AP Ezreal counters him very easily. Not really annoying.

Playing a caster against veig is annoying, but not impossible. The key is taking advantage of his poor early game. Even ability farming minions against his tower and heavily harassing him early is worthwhile. Veigar does get annoying once he's built enough to burst you down though. Even when you're sitting at double his CS and building better, he can still get off a hard hitting combo, so his stun becomes a huge zoning device. Just play aggressive early and back off when you need to. Other AP mid champions are far more valuable in team fights as Veigar's ult is single target, and his stun is able to be dealt with due to it;s long cooldown.

Personally, I feel that Viegar is A LOT like nasus. He has to farm him Q or his damage is greatly hindered. I feel that a really good counter to viegar is pantheon in middle since he doesn't go ap, and has nice burst potential with his WQ Epassive combo. So essentially Viegar (like nasus) has unlimited damage potential in a game but if you stop his farm he is not nearly as good.

ryze is also another good counter. He shouldn't be building AP until late game anyways

i still think veigar is good, his event horizon and dark matter combo is really strong. mostly becuz of the matter.

LOL!!! I played against you with veigar HAHA

Veigar generally has a very passive early game.
As Veigar the only thing I do pretty much up until level 8 is farm my Q.
You need to allot every drop of his mana towards Q farm or else you will not be hitting as hard later.

However, Veigar gets to both harass and farm if his jungle is smart enough and independent after first blue. A few good junglers that I've seen give me blue after a while to give me lane advantage. You don't need your W to farm, and you absolutely need your Q to farm, so it works out nicely. Use your W to harass your opponent and use your Q to farm. Your W doesn't even have to hit; you just use it because you have the extra mana to force your opponent to stay on his toes.

Once mid-game starts, you should still farm you Q as veigar whenever possible, but it's more important to score insta-kills mid-late-game, because those give you 5 AP for every kill, and it can stack up fast.

BTW, if you play AP Ez I will destroy you. Better to go AD.