Personally, what I'd want it for would be to have it replace PCLinuxOS as my general "go to" distro. For me, that was the best of the rolling releases for it was quite stable, and I liked the fact that I'd never have to reinstall the OS every couple of years.
I gave LMDE KDE a test run yesterday with a LiveUSB and tested out a few things that I found problematic in previous snapshots of LMDE. For example, after I'd play Armagetron, the screen resolution would go screwy on LMDE Cinnamon/Mate. It didn't do that on your edition, so props to you for that! Other things I noticed:
1. A KDE distro that idles at 200 MB?! I love it
2. After installing the additional codecs ("ugly" and "really bad") and putting in the needed workaround for VLC, music and videos played without a hitch. Flash had no problems either. Speaking of multimedia, I always wondered why Mint would ship with three video media players. I'm glad that you just picked VLC and left it at that.
3. Snappy, snappy, snappy. And in a KDE release at that.
Right now, I'm running Mint 13 KDE edition and have it set up how I want it, which is the only reason why I haven't pulled the trigger and installed LMDE KDE. Also, the fact that I have a 250 GB hard drive and a ton of music has prevented me from setting up a testing partition just for it. I think I might pull the trigger once the UP5 snapshot is released, though, because I'm really impressed.
Some issues, neither of which are deal-breakers:
(my computer is a Dell Latitude D620 laptop with 3 GB of RAM, for the curious, and I test-drove the 32-bit edition)
1. I, too, had that issue where I'd go to change the wallpaper and it wouldn't change right away. For example, if I change the wallpaper and click "Apply", it wouldn't change until I closed or minimized the Desktop Settings. Furthermore, if I change the wallpaper and click "OK", it wouldn't change until I right-clicked the desktop. It's an annoying bug, but nothing I can't cope with.
2. It didn't recognize both cores on my processor (it's an Intel Core 2 dual core). Nothing that can't be dealt with afterwards by installing a new kernel, but it'd be nice to have all my computer's cores recognized by default.
I haven't run into any of the others described in this thread, like the themes being screwy and GTK applications not looking right. That MIGHT be an issue with the version of KDE it's running, though, and not the distro itself. KDE 4.7 was buggy in places, which was a problem with Mint 12 KDE until I upgraded to KDE 4.8.
1. Ugly and really bad codecs installed by default.
2. Kernel that recognizes both cores installed by default for the 32-bit edition.
3. Wine and PlayOnLinux installed by default.
4. GIMP 4.8 installed by default.
(those last two are more personal)
Aaaaaaaaaand that's all I can think of for now. In the event I decide to install, I'll probably have more suggestions. As it stands, this is an extremely solid re-spin! Amazing job! This NEEDS
to be made an official Linux Mint release.