I know this is cliché, but nothing is free in this world.
I haven't gone to the website, but I'm assuming you have to do "tasks", in which some are extremely hard to qualify for?
Either way, the site's reaping the benefits of your hard labor. If you choose to participate in these tasks, go right ahead. I'm not stopping your or anything, but I'm simply pointing out the logic behind the "free".
Would I call it a "scam"? Not necessarily. The majority of "popular" sites out there that offer "free stuff" usually obligate you to complete surveys. The surveys are usually worth a minuscule amount of points. You'd have to complete a LOT of surveys to qualify for those free items.
Like dooman said, it probably is slow to acquire points. And like a few other people said in this thread, there's always a "catch".
Just thought I'd throw in my two cents.