This is a great example of WotC's ability to plan ahead in ye olden days. In a vacuum, this card is okay. You have to trade off a turn in order to get an extra turn later on (basically turning the game into one where each player takes two turns in a row). However, later development broke this card. Things like Clock of Omens, Captain of the Mists, Voltaic Key, and Rimewind Taskmage made it so you no longer had to skip a turn in order to untap this. As a result, it's been banned in pretty much everything it can be banned in. That's really it's only downfall: it's only playable in Vintage.
Pros: Lets you take extra turns
Cons: Vintage only
NOTE: Props to Mark Tedin for having fun with this card's art. I really like the idea that, somewhere in the multiverse, there's a couple of aliens who do nothing but make hourglasses that keep time going.