At the time of writing this, the openQA servers were busily running tests and, by the time we publish this article, they should be done. What was being tested? A massive amount of changes, bringing not only the latest Plasma 5.3 and Applications 15.04.1 to Tumbleweed, but also marking the switch to Plasma 5 as the default desktop!
Some of the biggest improvements in Plasma Desktop include much improved power management and widget handling. New are a touchpad configuration module, Comic widget and some system monitoring applets and improvements to plasma widgets like Clipboard, Recent Documents.