I'm very surprised there aren't more KDE appreciation posts on here. It's such a beautifully round piece of software -- customizable, yet reliable and unassuming.
It's exactly what the desktop experience, and software in general, should be: there for you when you need it, without making the entire experience about itself.
I don't have to actively think about my desktop environment when I'm browsing Hacker News on Firefox, or writing code, or listening to music -- it looks back empathetically when a program goes wrong, or when my workflow changes and it needs tweaking, and everything else.
You've made something brilliant, and it's definitely positively contributed to Linux's increase in market share.