This book's habit of tying into everything else is why I dropped it months ago. With 52, they only expected you to have already read several books. Infinite Crisis, back issues of X and Y, ect. They expected prior knowledge from their readers, which is the case with 90% of all comics.
With Countdown, they're basically saying "Sorry, Charlie. You won't understand a lick of this book unless you're currently buying the entire DC line." When I started reading Countdown, I was mainly only reading JSA. Imagine my frustration.
Countdown sucks, and I pity all of you who hate it, yet continue to buy it in hopes that the payoff in issue #0 will be worth it.