I agree with all other comments. The icons are almost impossible to identify, almost impossible to understand if a button is enabled or disabled. There is no color/contrast.
I really wanted to test the beta version but I simply cannot work with this new layout.
PLEASE KEEP THE OLD BUTTONS! I will continue to work with the default color scheme if that will be the only one with the old buttons.
IMHO I don't like "There will not be any option to go back to the old look." . Please listed the community/clients when a big decision is taken.