Being into animation, it's actually not that surprising. It's bright, colorful, simple and heavily marketed so people definitely know it exists. Those kind of films can make money, even though they gotta' go the route of flash over substance.
Question is will they be able to keep the momentum to reach $500+, since that's probably what they need before they start making a profit. It's no secret Rovio is betting the farm with this, it HAS to be a mega hit with the money they put into producing/marketing.