The KDE project recently released the first stable version of Plasma 5, a major redesign of the KDE desktop and underlying frameworks.

If you'd like to take this release for a spin there's a <a href="http://files.kde.org/snapshots/neon5-latest.iso.mirrorlist">live CD available from KDE</a>. To get a feel for how this release fits in with a more popular distro, I tested KDE with Plasma 5 in Kubuntu 14.04.

Plasma 5 is perhaps most notable for its visual changes, which see KDE embracing a more streamlined, "flat" interface, but it's also the first version of KDE to be powered by Qt 5 and the recently released KDE Frameworks 5.

The visual changes and the polish that's been added to the default Plasma theme is welcome -- frankly the default KDE 4 theme has been looking long in the tooth for a while now -- but it's the under-the-hood changes will have a bigger impact on the future of KDE.

Among the biggest changes in Plasma 5 is the "converged shell", which envisions a unified desktop future very similar to the goals of Ubuntu's Unity shell. That is allowing the interface to adapt to the hardware on which it's running. In this case the shell would select Plasma 5 for your laptop, but run it on a tablet and it would change to a tablet-based interface.

The new "converged shell" will be able to select which "shell" is used based on changes to the device as well. The canonical example being a touch interface on a tablet that, when it detects that you've plugged in a keyboard, would switch to an interface more suited for keyboard input. It's a little unclear from the KDE docs what happens if you want to use the touch interface <em>and</em> a keyboard, but presumably that's possible as well.

For the moment there's only the Plasma 5 Desktop anyway. KDE developers are working on both tablet and media center interfaces as well, but neither are currently available for general use.

The release of Plasma 5 also completes the migration of the Plasma workspace to Qt 5 and QtQuick, which uses a hardware-accelerated OpenGL scenegraph to render graphics. That means KDE can take advantage of the powerful GPUs in today's devices and offload some of the more expensive graphical tasks to GPUs. On supported hardware this should give you a bit of a speed bump, particularly when doing other graphics intensive tasks like editing photos or video. 

The changes to the graphics stack and underlying Frameworks also pave the way for KDE to support Wayland, which will be "part of an upcoming release".

Plasma 5 also claims improved support for HiDPI displays, but I was unable to get this working in a virtual machine on my Retina MacBook (the only HiDPI screen I have). I've yet to determine whether this is a problem in Plasma 5, Kubuntu 14.04, the fact that it's a virtual machine or some combination of the three.

When you install a fresh copy of KDE Plasma 5 on your favorite distro the thing that jumps out won't be better graphics or the potential to switch interfaces based on hardware. What will jump out at you is the new "Breeze" theme for the Plasma desktop.

Gone are the shiny, candy-like icons and darker textured grays that make up the default Oxygen theme in Plasma 4. Instead you'll find a lighter, brighter, flatter design aesthetic with a lot of monochrome icons, thinner looking type and frosted, slightly transparent windows.

As with anything design related, some of the new interface's appeal will depend on your own aesthetics. As someone who thought that the Plasma 4 default theme had pretty much nowhere to go but up, I think that Breeze is a huge improvement.

Compared to Plasma 4, Breeze is a giant leap forward, and not just visually, but functionally. The overall UI is greatly simplified -- things are much better spaced, making them less jumbled and easier to find and read. Most of the time anyway. Breeze isn't flawless by any means. For example, the window and overlay translucency is nice, until it isn't. Stacked windows and overlays often bleed through whatever is below them and look jumbled and sometimes hard to read.

Among the elements that have been reworked are the Kickoff app launcher, the notifications panel and the lock screen, which now offers time, date, and battery status in addition to the usual session management info. 

One thing to note about the revamped version of Kickoff -- there's no search field visible when the menu launches. To search you just start typing and a search field appears with your text in it. It's pretty much impossible to discover this feature, making it another example of not-so-great design in Breeze, one that hopefully will be addressed in subsequent releases.

In addition to Kickoff there's also a new, more traditional menu-like launcher called Kicker that makes a good, lightweight alternative if all you want is a fast way to launch applications.

The notification area seems to have dropped its Windows XP-inspired penchant for hyperactively spitting out notifications and alerts. I managed to use Plasma 5 for several hours without a single annoying pop up or alert, a considerable improvement over the last time I fired up KDE. 

If you opt to install the current version of Plasma 5, keep in mind that the Breeze theme is a work in progress, not all elements have been updated. Not all icons have been updated for example and some applications look a bit out of place. The version I tested did not, by default, use the new Breeze Window Decorations, though you can enable them in the system settings app.

It will be interesting to see what openSUSE does with the Plasma 5 Desktop. The openSUSE project's highly customized version of KDE has long been one of the nicest default KDE themes available. Hopefully that will continue and even improve with the somewhat nicer base of Plasma 5 to build on.

It's worth noting that seasoned KDE users may want to pass on Plasma 5 and its Breeze theme for a few releases as there are still some features from Plasma 4 missing in the current version. The situation is not as bad as the massive feature abandonment that happened in the move from KDE 3 to KDE 4, and the KDE design team plans to keep refining Breeze, adding back the missing features over the next few releases, but I suggest trying Plasma 5 first to make sure all your must-haves are there before you jump in with both feet.

By some figures KDE is the most widely-used Linux Desktop around. Ubuntu's Unity and Mint's Cinnamon may get more attention, but KDE remains a favorite by any measure and the Plasma 5 desktop shows the project hasn't forsaken the desktop experience in favor of "convergence". Whether or not a unified OS across devices is the right strategy remains to be seen, but KDE is at least doing it right thus far, not chasing devices at the expense of the desktop.

With Unity far more focused on devices and Cinnamon without any plans to build a device-friendly version, KDE fills a nice middle ground. 

KDE Plasma 5 makes an excellent desktop today and lays the groundwork for KDE to be part of the device saturated world of tomorrow.