maybe for the mobile version (flutter is early stage, so i didn't expect Google to use Dart there [https://flutter.io/]. The last mobile webapp i worked on was just replaced with a native version which runs smoother, so i guess native development beats webdev at the moment).
How about with the web version for desktop?
The announcement showed advanced ui-elements: [https://lh5.googleusercontent.com/GRV687LnnWpFCpPcQ6vxjd_kEQ...]
So a primitiv result there would indeed be a disappointment.
It might still be work in progress. I guess they started 4 month ago with the rewrite?!