I now am completely impressed by KDE. 
I started out as a GNOME user, then decided to try KDE, and I haven’t looked back since.
Of course, the choice of the desktop finally depends on the user, but still… I think KDE is simply GREAT!
That eye-candy desktop cube, those cool effects, and many other things… Another thing I like about KDE is that it contains better (in my opinion) applications than GNOME.
And that desktop cube… Well, it’s so good I can’t say anything enough for it.
Yup, no doubt in that, specially KDE4.3 onwards (exclude 3.5).
The great thing is, that how openSUSE integrate and implement KDE.
Mentioning Kubuntu here, KDE looks awful there but in openSUSE its really great implementation.
The whitish Air theme in KDE 4.3 is, in my opinion, much more ‘open-looking’ and good-looking than the previous KDE 4 versions. The Oxygen theme, although very sleek and stylish, was kind of buggy and seemed very Vista-ish.
Funny, this is always about the cube and other eye-candy. Never about how all these beautiful programs can talk to eachother, how they basically all work the same, about what fantastic phenomena Plasma and Phonon are.
On theming:
- Try the Aurorae window decorator. Themes aren’t too many yet, but looking very good, Aurorae is stable.
- In what way does Oxygen look like Vista?
- A last one: almost anything is themeable in KDE4, just look for it and you’ll find more than you can use.
I love KDE apps, but I actually prefer compiz to kwin, although I note that kwin have plans to introduce some of the stuff I feel it’s missing (like tiling).
But for me things like ‘scale’ just work better than the kwin equivalent ‘present windows’.
Should probably try KDE with compiz on at some point…
That black look is very similar to the Aero look. Although Aero does include an Air-type theme too…
Even on a low spec machine which won’t support most of the bling, it looks good.
Whenever I have the misfortune to have to look at someone else’s Windows machine, I am reminded just how good it is and how different it is from most other conceptions of what a computer interface should look like.
I like KDE 4.3 a lot. The only things I don’t like is the lack of drop shadows on top placed panels, the lack of a CD/DVD burner built-in into dolphin (not as a context menu, but built-in like in nautilus/MacOS finder), and the inability to use both “box” and “flip3D” switchers simultaneously (compiz sets flip3D to win-tab and the traditional switcher to alt-tab).
I am going to have to pull you up on that…
Why, on God’s green Earth, would you need both? Isn’t that just… greedy? 
However, even in its 4.3.2 incarnation (which I use), KDE is still very much a “work in progress”: the plasmoids are either useless, underfeatured, buggy or (mostly) all three (except Folder View). Which reduces the appeal of “activities” over virtual desktops to the different wallpapers… Assigning activities to desktops is possible, but currently at little more than alpha stage. Kwin remains slow with NIVIDIA cards at least, and using Compiz with KDE4 instead opens up new cans of worms. True translucency still hasn’t arrived for KDE4 window decorations, and don’t get me going on dual monitor support. The “to do” list is rather long…
AND YET, I use KDE4 because it’s like a breath of fresh air compared to Gnome and (even more so) the Windows GUI. Plasma has so much potential and looks so good, but I reckon it will be another two or three years until it’s mature.
KDE looks polished, but it’s interface isn’t all that polished compared to commercial OS interfaces like Windows 7, to some degree. The theme is good, many other good things, but Aero still wins over KDE in terms of eye candy, mostly with that window transparency. KDE is beginning to implement this function too (there’s an option to make the whole window translucent under certain conditions). KDE’s future looks bright, though.
I’m a big KDE-3.5.10 user, but after trialing KDE-4.3.1 on a sandbox PC, I elected to very gradually switch to KDE-4 on all the PCs in our family (total of 7 PCs). Why? KDE4 is good.
I’ve already moved our new Dell Studio 1537 laptop to KDE4 (installed from the community openSUSE-11.1 KDE-4.3.1 liveCD and then updated to 4.3.2). My sandbox PC dual boots between openSUSE-11.1 KDE-3.5.10 and openSUSE-11.2 RC1 KDE-4.3.2. My wife’ PC now has openSUSE-11.1 KDE-4.3.2 (installed from the community KDE-4.3.2 liveCD).
For the remainder of the PC’s, I’ll wait until openSUSE-11.2 (or 11.3) is available.
From my rather biased KDE-3.5.10 big fan user perspective, there are aspects to KDE-3.5.10 that I find easier and that KDE-4.3.2 does not offer the same for me as some KDE-3.5.10 aspects. But KDE-4.3.2 has things that KDE-3.5.10 does not have, and hence KDE-4 now has the edge for me.
I do note wireless management in KDE-4 is still awkward to setup. Typically even though wireless “just works” in terms of the kernel module/driver, the wireless management in KDE-4 does not “just work” and often one has to go to YaST to implement a work around (and/or also install wicd). I have wicd installed on my Dell Studio 1537 laptop, and now wireless works well in KDE-4.3.2, but in the process, wired no longer works as WICD ( ? ) or the application it interfaces to is blocking wired. This is not an issue as I use wireless all the time with this laptop, and I can always revert to the setup without wicd where wired does work. And given the other advantages of KDE4 over KDE3 (and from my perspective over Gnome) I can live with that networking hiccup.
I also find the pulse audio implementation in KDE-4.3.2 has hiccups that I do not have with pulse audio in KDE-3.5.10. However “hiccups” is the operative word here, as sorting such KDE4 pulse audio hiccups are for me rather easy.
For the nvidia hardware that I use, transparency effects work on KDE3 with an openGL driver but they do NOT work on KDE4 with an openGL driver. One needs a proprietary graphic driver in KDE4 (on the hardware I use) to get transparency to work. And there are disadvantages with a proprietary driver when it comes to kernel updates and the occasional xorg update.
These aspects back the point noted above, that more work is needed on KDE4 for it the real smooth/cool desktop that we all would like to see.
I still now prefer KDE4 (over KDE3) and think its now a good desktop.
Well, that’s a matter of taste really. Many people do not like the glassy look of Vista/7 and many people do like it. In KDE4, I use the Bespin style and I like it much more than the default Oxygen one of KDE4. If you haven’t seen Bespin yet, here’s a screenie ImageBam - Fast, Free Image Hosting and Photo Sharing