Good God, it's good. I'm in love with this cake. It's the BIGGEST angel food I've ever made...and it ought to be w/ 16 egg whites. Beautiful, the top cracks and lifts like a souffle.
The chocolate is surprisingly chocolate-y. I've made "chocolate angel food" before, but it was a bare whisper of chocolate. This recipe calls for 1/4 cup of boiling water mixed w/ 1/4 cup + 1 T of cocoa. I used Valhrona. It was as dark colored as many non-angel chocolate cakes.
I think it must be the addition of the water that changes the texture just slightly. It is a little bit moist...hints of chiffon cake, and very tender. It was nonetheless sturdy, cut easily, had no air pockets.
I can't recommend it enough. I have never understood how anyone could dislike angel food cake, but I understand that many do. This one seems less sweet because of the cocoa, so this would be the one for angelfood skeptics to try.