Prominent features of KDE Plasma 5.5 include enhanced activity switcher user interface, the addition of a new Activity Pager applet, updated Breeze Plasma theme, which is now more consistent and improves the visual design, along with the implementation of a two column view for the Plasma Widget Explorer.
Furthermore, KDE Plasma 5.5 re-implements the Color Picker applet, which now boasts a revamped interface, adds support for accessing the User Switcher applet from the Application Launcher, adds an all-new Disk Quota applet for viewing allowed quota and overall usage, as well as re-implementation of support for legacy tray icons.