In an ongoing mailing list thread, the Ubuntu Technical Board is discussing whether the new Unity environment is a suitable default for the upcoming Ubuntu 11.04 release, codenamed Natty Narwhal. The prevailing view seems to be that Unity is still on track, but there are a number of technical issues that are still being addressed.

Unity is a new user interface shell and window management system that is designed to improve Ubuntu's ease of use and visual sophistication. A previous version of Unity served as the netbook user experience in Ubuntu 10.10. The plan for 11.04, codenamed Natty Narwhal, is to ship the much-improved new version of Unity as the standard user experience across desktop and netbook form factors.

Unity introduces a universal menu bar, a vertical task management dock that is anchored to the left-hand screen edge, and a set of overlays called "lenses" for accessing files and applications. Implemented as a plug-in for the Compiz window manager, Unity makes extensive use of compositing and hardware accelerated rendering to deliver elegant visual effects.

Many of the concepts behind Unity were drafted by a team of professional designers and software usability specialists with the aim of significantly improving the Ubuntu user experience. Their close attention to detail shines through in many aspects of Unity. The menubar is clean and highly functional. The sidebar dock is visually appealing and has excellent default behaviors for automatic hiding.

Although there is a lot to like in Unity, there are some aspects of the Unity environment that still feel unpolished and poorly thought out. The interface for browsing available applications sticks out as a particularly weak part of the user experience. The mechanism for switching between application categories is irksome and visually tacky. The lists of random packages from the repositories, which are presented as applications that are available for installation in the launcher, are distracting and largely superfluous.

Developing a complete user interface shell is a significant undertaking. The plan to deliver a new Compiz-based version of Unity in 11.04 seemed tremendously ambitious when it was presented at the last Ubuntu Developer Summit. It wasn't clear at the start of the cycle whether it would be ready on time. The most recent assessment of the desktop team and the Ubuntu Technical Board indicates that it is still on track.

In a mailing list post written this week, Ubuntu engineering chief Rick Spencer briefly outlined some of the remaining technical issues in order to open up further discussion about potential roadblocks. Bugs like crashers and memory leaks are said to be well under control.

"The Desktop Team still feels strongly that Unity will provide the better experience for most users, is stable enough to ship, and will be more stable by the time final media is spun," wrote Spencer. "In terms of the instability of the system, the Desktop and Dx teams report that most remaining instabilities in Beta 2 are crashers related to making changes in ccsm. These crashers, and the other known widespread crashers are either fixed in Beta 2, or are scheduled to be fixed in the current Dx milestone that ends this week."

Canonical's uncompromising commitment to conforming with the schedule of Ubuntu's time-based release cycle sometimes encourages a no-such-thing-as-a-blocker mentality that is not entirely conducive to robust releases. At the start of the Natty cycle, there was room for concern about a premature Unity release detracting from the quality of 11.04. It seems to be in good shape, however.

In such a far-reaching user interface overhaul, good first impressions are extremely important for achieving user acceptance. Spencer has set the right tone during this development cycle by defining high quality standards for Unity and subjecting it to disciplined scrutiny at regular intervals.

There is still a lot of room for improvement, but Unity is arguably a strong improvement over the conventional GNOME 2.x environment for day-to-day use. The breadth of the changes may be disorienting for some users, but most will like what they see when Unity lands on their desktop at the end of the month.