I don't think it is a scam either (not much to be scammed with other than your time and effort).
But I do think it is too good to be true and thus not lasting for a long time.
"free" stuff like this usually gets down very fast, especially if it gets popular. They promise a lot now to attract users, but in a few months time the 'rules' will change and it will be way harder to earn points me thinks.
It simply doesn't add up if the steep rate of points earning stays the same after the launch etc. Nobody will do something like this on a permanent basis to simply give money away. They need to make a profit too. And by simply showing ads or sending emails I can't believe they will earn enough to have a profit after the deduction of the costs of the prizes from all the users. Hence I'm a bit sceptical and think the system will change rapidly after the launch and it wont last. So, or the prices will increase in points a lot, or the validity period of your points will be decreased after the launch or whatever. I don't see this going on for a long time with those current same conditions.
Anyways, go for it by all means and make as much points as possible and proof us wrong I'd say
(and make me jealous)
/ 
