Its like comparing peanuts with Cashew nuts. The present DD runs as over Night starts at around 11 pm.
UDAY is ICE , Starts around morning 6 am and teaches by 10:30 am. It is planned as capital connectivity. Travel timings are important in mode of transportation. So no comparison with DD to UDAY.
Yes one Janshatabdi should have did good job instead of UDAY. But what railways gives we have to take it.