Good video, very much worth watching despite the length. New UI will look something like this:
with an option for a more classic look.
Looks like an enourmous UX improvement too, and a rewrite to QT and eliminating a lot of technical debt will make development faster.
It's looking freaking gorgeous. Tentacrul is the bomb. His work on MuseScore is arguably the best UX/UI in the FOSS world. It even beats most if not all of the proprietary alternatives in the same category.
He also did a great tribute video to Tim Smith / Cardiacs. Was already in my good books, went beyond with that one.