First of all, please let me apologize in advance for not including QNX's Photon, OS/2's WPS, Amiga Workbench, Solaris' CDE, IRIX's 4Dwm or other X11 desktop environments in our comparison. While I have used all the above during the last two years, I don't have them readily available on my machines anymore (for example the SPARC and Octane & Fuel review boxes we received last year were returned to Sun and SGI respectively), so I decided to include in this test only operating systems that I can reboot at any time and test them more thoroughly when and if I need to.
Also note that this is a quick overview. We can't possibly cover these environments in-depth, as that would take not five pages, but probably one hundred and five. I am sure that our readers will agree on some points while they will disagree on others. This is fine and normal, so please keep the discussion in our commenting area intelligent and calm. What we are comparing here is the overall user experience generated by these desktop environments and their underlying OSes.
I include the BeOS in this comparison not because I consider it an OS with a bright future but because it was very highly regarded in its heyday and it still good (in other words, even after 2,5 years of the last update by Be, at least in the desktop area, not many OSes have managed to surpass it yet).
Third note: what we are testing here is not just how things look. The "eye candy" factor is just one of the many factors that makes a DE great or... sucky. Some other factors are when a DE is easier to use or more "delicate" or more speedy than another, or more consistent or more integrated. But let's start with the looks, as it is the first thing someone will notice when first loading a graphical DE.
The Look and Feel
I recognize that this part is kind of subjective. Some like small fonts, some like bigger fonts, some like funky buttons, others like....
Nevertheless, no matter the different tastes, there is always a threshold line where the majority of people will define as "good", while under that line would define as "bad" all in one voice. Speaking for myself, I like clear as crystal widgets, with big window manager buttons that no one can miss, and as the perfectionist I am on this subject, I want the UI I am using to be pixel-perfect.
Starting with Windows XP's Luna interface is not the most pretty one. But it is the most logically designed one. Its widgets are well defined, while special care have been taken to the way things work in a way most people expect or are accustomed to. It is clear to me that the Windows interface is pretty mature and most issues have been ironed out since 1995. However, this all-blue default color on XP is kind of 60's psychedelic, it gets on my eyes soon enough. On the bright side, the fonts are great, the font shadow on the desktop and window manager is great looking too, making them easier to read. By default the Windows XP interface doesn't enable antialias on its fonts, but Windows is making use of some very high quality fonts so they don't look bad at all, even without antialiasing. With XP, the Windows graphics interface is now more skinnable than ever, however the majority of the users that use Windows stay with the defaults.
MacOS X has probably the most in-your-face eye candy of all the DEs compared here. Some don't like this 'lickable' interface while others simply love it. My opinion is that the Aqua interface has seen a clean up with the release of OSX Jaguar 10.2. The button quality is much better now, for example. I am quite happy with the way Aqua looks even if it is not skinnable without the use of some scary hacks. The metal interface seen on some Cocoa apps is an interesting idea, but it is not as easy to read text written on top of the metal surface (for example Safari's new tabs in the latest unreleased beta are pretty much unreadable without wearing glasses). It is also great to see brand new widgets into the play, like the drawer or the animated alert window attached to the master window. All in all, an innovative and fresh look when it was introduced 3 years ago.
KDE is compared here with its new default theme, Keramik. Personally, I dislike Keramik (for the most part). I find it clunky, extremely loose on details and too much in-your-face. The Qt toolkit actually doesn't seem to have much of a good support for what Keramik is trying to do. For example, I get Qt or KDE applications not supporting the background gradient Keramik is trying to impose on the back of toolbars, and so we get some apps having some toolbars with the intended color or gradient, and some other toolbars on the same app don't (and that's ugly). That might be an app bug, but it is so common (even on KDE's KOffice) that it reflects badly on the whole experience. It doesn't matter whose bug it is. The point is that it is there. The buttons are so overwhelming that sometimes their text goes unnoticed (at least they should either bold or shadow the text on these kinds of buttons to expose their importance). I also don't like its window manager buttons, I find them clunky. Its tabs are so not part of the tab view, they feel alien to it. I do like other widgets offered by Keramik, but the most important widgets are either overwhelming or they lack care on their details. Have a look here for more info on my gripes on that theme (discussed on the kde-usability list a few months ago). Thankfully, KDE is fully themeable. The icons are nice on KDE and their alternatives, like the Noia icons, are great looking too. But Keramik is not.
Gnome is compared here with both its default GTK+ theme and Red Hat's BlueCurve (Red Hat is the best selling 'Gnome reseller' so most of the Gnome users will be using BlueCurve, essentially making that theme virtually a "second default" for Gnome). So, Gnome is not going to get any praises on having a great looking widget theme, but overall it ain't ugly either. Its widget set is very plain (both BlueCurve and especially the default GTK+) but it doesn't try to be 'something else'. The window manager looks of BlueCurve is nice and clean. Its buttons are big and easy to reach and this is a plus. The Gnome/Red Hat icons are not as good as MacOSX's, XP's or KDE's though, but are definitely better than BeOS' (the default BeOS icons were great in their time, but they have been surpassed now).
As for BeOS [6/Dano/Zeta]'s looks, it was an improvement and a step backwards compared to BeOS 5, at the same time. Today, the BeOS legacy is continued by YellowTAB's Zeta product, while there are still a large number of active users of the BeOS 5. Fonts are way better on the Dano/Zeta version of BeOS than before, the Interface Kit is now more themeable (but not fully), and it now supports non-rectangular windows. However, the widget set has seen great innovations and back-steps. For example the Z-Snake effect as seen in the screenshot is a great eye-candy effect (and pretty complex programming-wise), the radio buttons have this clever "switch" while combo boxes are also having animated effects and they also use the Z-Snake when enabled. On the down side, you will find terrible looking buttons, small default window manager buttons that need to be aimed with a gun and not with a mouse...
Rating: (out of 10) Windows XP 8.0, MacOSX 9.0, KDE 6.5, BeOS 7.0, Gnome 6.5.