Canonical has announced the official release of Ubuntu 11.04, codenamed Natty Narwhal. This major update introduces the new Unity desktop shell, which is designed to improve ease of use and deliver a more modern user experience.

Ubuntu founder Mark Shuttleworth unveiled the Unity project a year ago during an Ubuntu Developer Summit keynote in Brussels. The new shell was originally created for the Ubuntu Netbook Edition and first shipped as the default netbook environment in Ubuntu 10.10. The Ubuntu developers have worked intensively over the last six months to adapt Unity for the desktop. The effort entailed a significant overhaul of the Unity frontend that boosts its performance, reliability, and suitability for use on larger screens.

The new Unity-based desktop shows a task dock on the left-hand side of the screen and a panel at the top with an embedded global menu. A screen overlay that emerges from the top panel provides access to additional features through modular content panels called "lenses." The default environment comes with an application launcher lens and a file management lens.

Although many of the changes introduced in Unity represent tangible usability improvements, there are some parts of the environment—particularly the application lens—that still have some rough edges. Some users might also be put off by Unity's lack of configurability. The position of the dock is one of several key aspects that can't be customized. Users who prefer a more traditional environment or want to wait for Unity to mature further before making the switch can simply choose the "Classic" Ubuntu desktop in the system login interface.

Unity requires support for hardware-accelerated rendering, which might not work consistently across all hardware. The classic environment is also used as a fallback for users with unsupported hardware. A "2D" version of Unity, built with Qt, that doesn't require compositing is under active development and could serve as the fallback in future versions of Ubuntu. The 2D version is shipping today in the Ubuntu ARM netbook port, but not on the regular Ubuntu CD.

In addition to delivering the new Unity shell, the new version of Ubuntu also brings some improvements to desktop theming and bundled software. The Gtk+ theme has a new slim scrollbar style and a number of other enhancements.

Ubuntu's Software Center, which allows users to install and manage applications, got several noteworthy new features, including support for posting ratings and reviews. Canonical's Ubuntu One synchronization service got some nice user interface improvements and performance optimizations. The default music player in Ubuntu changed from Rhythmbox to Banshee in this new release, improving the out-of-the-box music experience for end users.

There is a lot to like in Ubuntu 11.04, but also a lot of room for improvement. We will give you an in-depth view of Unity next week in our upcoming feature-length review of Ubuntu 11.04. You can also download it for yourself today from the Ubuntu website.