I applied for the card back in March when it was first available, and have been using it ever since. So far (I just checked my balance) we have 50 DDRD in our account. But then we use it for everything--food, gas, clothes, everthing. And we also pay the entire balance off every month.
I haven't cashed out for the rewards yet, so I have no experience there. I was planning to wait until closer to our trip (in case something happens and we can't go--the points are good for 5 years, the certs are only good until Dec. 2004 right now I believe). I was planning to use them for food wherever we can at the parks/resorts.
There may be better cards out there, but I'm not sure the MyPoints card is one of them. You earn 1 pt for every $2 charged. Not taking into account the points you would get for shopping online, to get a $10 webbie, you need to spend $3000, to get a $25 webbie it would be $7000. On my Disney Visa that's $30 and $70 worth of DDRD. That's just how I look at it, and just my opinion. Of course you could use your MyPoints points for other things, non-Disney. But since my brother is a DVC member, and we plan to go to Disney a lot in the future, for now I'm sticking with the Disney Visa.