I was excited to see this posted, and hoped it would be what I had been looking for. My friends and I had not yet found a suitable World Cup prediction competition site.
I immediately signed up, and was ready to send off some invites, when I found that Scoragora wanted me to predict a score for each of the 48 matches in group play, a fairly tedious exercise. Further, upon completion, it is completely unclear whether the game will be calculating winners and runners-up from the groups automatically, whether there will be an opportunity to pick winners in the knockout rounds—basically everything after group play is a mystery.
Suffice to say this is not what I expected. I can understand some need for score predictions—most likely in the later rounds for tie-breaking purposes (perhaps the best way to handle this is to ask users to predict the cumulative goal differential of the winning side). But score predictions ultimately aren't the core functionality of a game like this. If I predict that Brazil will defeat Mexico 4-0, and my friend predicts that Brazil will win 4-1, I don't really care who was right about the score, we both rightly acknowledged that Mexico is a shambles at the moment (poor Chicharito—he's only 26!) and that Brazil ought to win.
The functionality I expect to see front-and-center is, simply put, predictions about who wins each match through the final. I truly can't tell whether that functionality exists in Scoragora right now, and I don't really care to predict 96 scores for the privilege of finding out. Moreover, I'm the geek in my group of friends, there's at least some chance I might fill out the entire prediction form to satiate my curiosity about how you've constructed this web app, but I'm certain none of my friends will have the patience to do so, so I won't be inviting them, and we'll conduct our competition elsewhere.
UPDATE: I've just tried out Yahoo's game, and theirs is structured almost identically (though a bit prettier), so maybe my expectations are out of line? I don't understand why the game basically resets when the knockout rounds begin. If i predict that Spain and Chile will get out of their group, and a friend predicts Spain and the Netherlands, and another predicts the Netherlands and Chile, there should be some benefit for the one made the correct prediction and some penalty for the two who didn't.