I did the $100 credit sonycard deal about 1.5 months ago. Everything went flawless - received my credit in 5 days. Just use the online banking access at chase.com to monitor your card after purchase and make sure you get the credit.
Another cool thing about this is that you get sonystyle...
Just a quick update on this. After applying for the sony card I received the card 8 days later. Bought the PS3 the following day. 3 business days later the 100 dollar credit was posted to my sony card account. New PS3 for 299! Can't beat that!
First, you must apply for the Sony card using the correct link. There are 2 sign-up links out there; one states that you must buy the PS3 from a Sony Style Store. The other states that you can purchase it from any authorized retailer. I am not sure if Gamestop is an authorized retailer...