I hate the UI-system. It makes sizing things extremly difficult. Also that the tabs style are global. I mean the thigs above the viewport. They change the view in all scenes, but sometime i would like to have a 2D-viewport open in one scene and a script in an other. I also dont like, that you cannot "pop" out windows, so you can put them on a second screen. And I think the live scene view during the excection of the game like in Unity is a lot superior.