In the world of *nix FOSS desktop environments, you generally have three choices - you can use GNOME, KDE or cobble together something from the various window mangers, file managers and other trimmings available out there on the Internet. The latter is the most complicated, and the first two are the most well-integrated and most convenient, which is why they are more likely to be tied to distributions.
There’s often in-fighting between GNOME and KDE users about whose desktop environment is best. A bit like the vi vs. emacs argument. Each environment has its own advantages, but each has his own preference.
Linus Torvalds, the creator of the Linux kernel, is a vehement KDE supporter. He dislikes the fact that GNOME is less configurable than KDE and that it apparently mollycoddles its users.
However, I’m on the opposite side of things. There are many things I dislike about KDE, and I’m going to list some of them here.
For starters, it seems to be very egotistical. Everything has some connection to the letter K, and it’s just ridiculously in-your-face and n00b-unfriendly. Remember that the average Joe User can’t tell the difference between his OS and his desktop environment, so there must be a lot of ‘K’ keys on keyboards out there with worn out springs.
Another irritation is its pointless flamboyance. Why does the tooltip automatically animate on with a circles animation? Why is there a silly bouncing icon next to the cursor when an app is started? This is pointless. There’s no reason why it can’t be available if asked for, but the eye candy switched on by default should only be that that is explicitly productive.
Then we come to Konqueror, The Most Pointless Piece Of Software In History. I don’t want to use my file browser as a web browser! You might as well go the full hog and get it to launch every application within itself when a document is selected. And Konqueror’s HTML rendering is sometimes simply awful. And why perform this function when Firefox will do exactly the same?
Another thing that irks me is that it’s just plain ugly. Most of it looks like a cheap rip-off of Vista/OS X, but so poorly executed it’s laughable.
Take this screenshot of KDE4’s default desktop as an example.

I mean, look at that. It’s awful. The default choice of font is awful (why not FreeSans?) and I detest the kickoff button and the clock. I mean, why does the taskbar have to be SO big? It’s twice as big as it needs to be, and that little reflection, both on the taskbar buttons and at the top of the panel, is completely and utterly awful.
True, GNOME uses a font like Verdana as its default, but it’s easier to change. And KDE is also far more buggy than GNOME in my experience, and it also seems ridiculously unprofessional.
I mean, why have a dragon amongst some clouds in the login window by default? Cutesy mascots should NOT be default. And when I installed Kubuntu in a virtual machine not so long ago, I was continuously plagued by sound problems, ugly notifications and the fact that KDE had lost its helpfile index.
In a way, KDE is like that idiot who used to be in your science class at school. He would always be the only person in the school to break the class cock-o-meter, would spend most of his day farting around and being an idiot, and then complain to the teacher because he hasn’t got a pencil. KDE is just so unprofessional and pointlessly flamboyant and bloated, I simply can’t see why anyone would describe it as ’sexy’.