Tonight, we tried the Coca-Cola flavored Oreos and the Oreo flavored Coke Zero.
Both of them were really awful. The soda had a little bit of Oreo flavor, but it mostly tasted like some generic brand of diet cola. The cookies didn't taste like Oreos (which I don't like anyway) but it didn't taste like Coke either.
They're just really bad. They did a poor job of reproducing each other's flavor, and in the process they lost their own specific flavors, too.