During the Cold War era, when USSR held their annual military parade at the Red Square I doubt the generals at NATO were peeing in their pants. I bet theparades weren't the main concern they had about USSR's military prowess.
Anyways India, another country with a powerful military, have been doing such military parade every year during the 'Republic Day'. I doubt all the military observers were sitting with a notepad jotting down all the latest development India had made to their defence capabilities, when all they could do is go on the Internet and get the information they want.
Such parades are nothing more than a trailer to what the country has in store. Like movie trailers, the juicy parts are shown to the world, to prove to the global audience that the rest of the picture is as good as the trailer shown.
The information tidbits on China's military prowess that can make the military strategists sit up and take notice are the ones that are closely guarded by the country and not the ones that are on open display. So all in all, there is not going to be anything new we can learn from this parade. Except maybe for learning how well the parade was.