Yes. You can use Disney Gift Cards at all of the Resorts and Parks ticketing, merchandise or dining.
The only exception is there was a promotion a few months ago where for every $100.00 Disney Gift Card you bought, you received a $10.00 Gift Card valid in The Disney Stores; these cards are not accepted at WDW
Do the restaurants not owned by Disney accept the Disney gift cards? I'm specifically thinking about the ones at the Swan/Dolphin and at DTD (Blue Zoo, Kimonos, Il Mulino, Shulas, House of Blues, Portobellos, and how about Bistro de Paris).