Vivid Vervet Doesn't Have Much Meat on Its BonesYou will not see much new in Ubuntu 15.04, aka "Vivid Vervet," unless you peer under the hood. The release of Ubuntu 15.04 for the desktop includes mostly maintenance and bug fixes, along with new integrated menus and dashboard usability improvements. Perhaps the most significant technical change in this desktop release is the adoption of Systemd to replace the default init manager system.
Source:
Vivid Vervet Doesn't Have Much Meat on Its Bones