With the latest Kubuntu 15.10 (Wily)
I love the KDE desktop—I really do. However… here are some grumbles.
1. If you're looking to configure wacom drivers using the KDE systemsettings Input icon, forget it. This functionality is missing from the (upgraded) KDE tools. If you do click the Input icon in systemsettings, you will find that your graphics tablet is configured as a joystick. So, you'll have to use the Command Line Interface xsetwacom utility program available in the xserver-xorg-input-wacom package. The xsetwacom utility is difficult to master.
2. If you use multiple desktops, under KDE4, you could use different wallpapers, and widgets for each desktop. Since I have a 3-monitor display, this was invaluable for tracking my applications and widgets, and setting-up a smooth workflow. This is gone from the new KDE Plasma5 and is not likely to be reproduced in the future (it's “too difficult”).
3. In the file manager Dolphin, you used to be able to right-click on a file, and click “Extract here” – which is a feature I've used probably a thousand-times over the years to expand files from the file manager into the proper folder. A nifty and useful utility in a file-manager (and not all that hard to implement). Well, it's gone.
So how do I feel about the “upgrade” from KDE 4 to the new KDE Applications15-Frameworks5-Plasma5? I guess it's better than switching from KDE3 to KDE4, but it's still aggravating. Yes, I know, it will take time before it's all polished-up (but, some things, like item #2 above, aren't likely to be fixed).