To my surprise, It turns out I quite like the Key Lime, and I was not the only one. The key is the unique graham cookie they created for this, which was crisp and truly did evoke a buttery graham cracker crust. (I'm glad they did not use the ordinary "golden" Oreo wafers, which I'm not a huge fan of.) The graham cookie contrasts nicely with the filling, and if you're feeling generous, you can *almost* invoke a memory of Key Lime Pie. The pale neon green filling was the thickness of a Double-Stuf, and the flavor had the bright lime pop of a Jelly Belly jelly bean. It was, however, a touch too sweet. It would have been better if they'd had the courage to really let the tart Key Lime essence shine.
Friends commented that it tasted like a green Lifesaver or a Fla-Vor-Ice freezy tube from childhood. One said "this tastes like green - just the color green." One detractor was reminded of "floor cleaner."
This was simply not as good as it should have been. I KNOW! How do you screw up filling a chocolate cookie with brownie batter? This should have been a no-brainer, but alas.
The filling did not taste of brownie batter, brownies, or even chocolate for that matter. The flavor was precisely that of a Tootsie Roll - distinctively "chocolate-y-ish." It was not offensive, necessarily, but definitely not anything you would ever confuse with actual chocolate, let alone with the unctuous heaven that is actual, cocoa-y, eggy, sugary brownie batter.
The texture of the creme was a bit unusual - it had a certain graininess, which brownie batter actually does. In the case of real brownie batter, however, this comes from the mixture of sugar and butter and cocoa. As you eat a spoonful of real brownie batter, those dissolving crystals pop in the mouth, contrasted with the smooth paste of the batter. In the Oreo, this texture was just faintly unpleasant. I'm actually guessing it wasn't there on purpose.
I suggest that instead of consuming these Oreos, you go eat a spoonful of real brownie batter, or even chocolate cake mix, instead. Just be sure you add the raw egg first. That's where all the fun is.