Duck in egg is a popular treat in Laos and many parts of Asia not just in the Phillipines. I am not sure it will catch on in western countries however.
I have eaten it. It tastes mostly like egg with maybe a bit more chicken/duck flavour. It is easier to eat if you dont look at it.
check out this video of a duck in egg eating "contest" in New York from the Sydney Morning Herald
http://media.smh.com.au/national/selections/a-foetal-attraction-3584924.html