When users talk about the latest generations of Linux desktops, almost always they report general impressions. They say that GNOME 3 seems needlessly complex, or that Unity seems too basic, but they're vague on the specifics. In the past, I've been guilty of dealing with impressions myself.
But what, I wonder, is the real story? In the hopes of providing some substance, I've to compare GNOME 2 and 3, KDE, and Ubuntu's Unity, using seven basic tasks that anyone using a desktop is likely to do. The comparison is not just a matter of mouse-clicks -- although that metric is sometimes revealing -- but, in some cases, a matter of design as well.
I haven't included KDE 3 because, despite last week's release of the Trinity Desktop, nearly four years after the start of the KDE 4 series, KDE 3 no longer seems a major desktop. Probably, however, its results would be similar to GNOME 2's.
In each category, I've awarded points according to how each desktop ranks, with the lowest score being the best. The results suggest something about the design philosophy behind each desktop -- and also produce some unexpected results.
GNOME 2 and KDE are the easiest desktops from which to start an application. Both support icons on the desktop, which are launched with one or two clicks, depending on your configuration choices. If an application is not on the desktop, then both average three clicks to open it from the menu. GNOME 2 edges out KDE because the default KDE menu may require some scrolling, which slows the launching.
By contrast, the effort to launch an application in GNOME 3 varies considerably. If the application is on the dash, launching requires two clicks and a change of screen to the overview. Otherwise, you have to click Applications. With a fourth click, you can open some popular applications, but otherwise, you'll need a filtered search and another click to start the application. As the application starts, you return to the main screen, which may be confusing for new users.
In Unity, you need one click if the application is on the dash, plus some scrolling if the icon is collapsed. If you've created folders on the desktop, you can start an application in two clicks using a document launcher. Otherwise, you need to click the Dash Home, and either click a common task or select another category, where you need another click and possibly some scrolling. Alternatively, you can search if you know what's likely to be available.
Verdict: If you only consider defaults, GNOME 2 is the winner, followed by KDE. GNOME 3 and Unity can match the performance of the others, but only if you're lucky, so they are tied for third.
In GNOME 3, Unity and KDE, a search field is only one click away. Each has automatic completion, which can be convenient, but sometimes requires scrolling before you make a selection. Unity's automatic completion is particularly annoying, because if the last results don't form a complete line, it simply indicates "See more results." GNOME 3 includes buttons for Wikpedia and Google searches, which seems pointless considering that you are searching your hard drive and home directory.
Provided you have enabled Nepomuk and indexing of files, KDE's search results are by far the most powerful, returning results for anything on your computer. The weakest is GNOME 2, which has only file searches and a list of recent documents, and whose menu has no way to search for applications except visually.
Verdict: KDE, GNOME 3, Unity, GNOME 2.
All four desktops have features to make regularly used applications more accessible. In GNOME 3, you can add favorites to the dash (although it is a screen away), in Unity to the launcher. In KDE and GNOME 2, you can add desktop launchers for favorites, while KDE's menu includes Favorite and Recently Used filters.
Verdict: KDE gives you the most options for retrieving favorites quickly. The rest are more limited, so I've declared a three-way tie.
GNOME 2 uses a classic menu, in which sub-menus expand over the desktop. With a large number of menu items or levels, this design can be cumbersome, although it has the advantage of being easy to navigate.
At the opposite extreme, GNOME 3's launcher and Unity's dash offer a limited number of basic and favorite apps on the left side of the screen, leaving complete menus to full-screen displays that take the user away from the windows in which they are working. Unity's dash has a slight edge over GNOME 3's launcher, thanks to the collapsible menu items, which allow you to store items efficiently while still seeing what they are.
Between these opposites, KDE offers a compromise, confining the menu to a single window. The scrolling this arrangement requires is less than ideal, but you can click on the menu button to get a classic menu, or select Lancelot from the set of widgets for a compromise between the default and classic menus.
Verdict: All these approaches to menus have their problems, but KDE wins first place by offering a choice. After that, GNOME 2's classic menu is the most usable, followed by Unity and GNOME 3 in a tie.