First of all Gifts Ungiven has been restricted. Meandeck Gifts won the world championship back in 2006.
The original primer/list can be found here:
http://www.starcitygames.com/php/news/article/9963.htmlThe actual list that won the world championship is here:
http://www.wizards.com/default.asp?x=mtgevent/vintage06/welcomeBasically if you take the World championship list and do this:
-3 Gifts Ungiven
+1 Empty the Warrens
+1 Skeletal Scrying
+ Thirst for Knowledge or Misdirection
Then you still have a decent deck, but you lose the combolicious abilty of Gifts Ungiven.
In general Gifts would not be that good in today's metagame. Having said this, it seems to be thriving in Europe.
The idea of Gifts was to Gifts for:
Yawgmoth's Will
Tinker
Time Walk
Recoup
Frequently you already have 1 in hand so you can add Black Lotus.
If you get Yawgmoth's Will you just win.
If you get Tinker and Timewalk then you Tinker for DSC and then Walk. Next turn you Flash back Recoup to Walk again.
If you get Tinker and Recoup and you have enough mana you Tinker out Black Lotus and then Recoup Will for the win.
If you get Time Walk and Recoup then you can Walk to get more mana in play and then Recoup Will.
After playing Yawg Will you usually Tinker for DSC and then Time Walk. You also use Scroll to Find Mystical to put Burning Wish on top.
You take your Time Walk turn and swing for 11 with DSC. You then Burning Wish for Time Walk and take a third turn swinging for lethal damage.
Even if DSC is blocked you can then Recoup Time Walk for a 4th turn!
The other way to win is to use Chain of Vapor or Rebuild to get a lot of mana / storm and then Burning Wish for Tendrils of Agony or Empty the Warrens.
You will notice that all of these require a lot of Mana. Meandeck Gifts was a varociously mana hungry deck. It basically ran 17 mana accelerats if you count all 10 artifact accelerants, Academy, Chain, Rebuild and the Mana Drains.
Meandeck Gifts was so mana hungry that Giftsing for the 3 on color Mox and Mana Crypt was a fairly common play in the early game.
Against Mana Denial you fetched out Basics and then you could either Mystica, Vamp or Demonic for Tinker or even Gifts for all 3 Tutors.
Against Graveyard hate you could use the same strategy for finding Tinker. Also you could Gifts for Gifts, Fact, Scroll and then either Drain or Brainstorm.
The idea is that you probably get Brainstorm/Gifts or Drain/Gifts and you can chain together draw and try to ignore your yard and just win with card advantage.