In old UI navigation was easier. For example now i'm in upload image doc, it'll show all other upload api endpoints methods in the leftpane. but in new UI it's not showing like that. There's a lot of UI breakages in new one.
And old one's color was pleasant left pane with 'summer sky' (#25AAE2) color for texts, it looked cool. But in new UI dark blue color texts on the background is somewhat makes me feel uncomfortable. And top bar with slim blue gradient is also not seems good.
I feel 'Summer sky' (#25AAE2) color is twitter's brand color, but that is missing in new UI and overridden by dark blue color.