Even if admin2pp is clearly a possible model (as the author of it I can't say the opposite :-)), some parts probably need some work because a part of the configurable dashboard code is there to properly override the default dashboard, the JS needs a bit of refactoring...
In addition, this extension is based on jQueryUI but the current admin interface is mainly based on some widgets from YUI2 (datatable, calendar, multiupload, ...) and some others from YUI3 (auto complete when eZ Find is there) and jQuery for some AJAX calls and basic DOM operations I think this is already too much :-)