Well, I'll try to describe the most annoying things in KDE4. First of all, as already mentioned, it's gigantism. Take for example Plastik theme in KDE3.5 and its much worser version Plastique in KDE4. Even with the same fonts Plastique has larger buttons and menu bars as if they were designed for Chinese ideograms. Next is sharp lines. KDE3.5 was advertised for it's sharp lines compared to Gnome. You can read about it even in the 'about' box. But KDE4 becomes inverse of it. You can also compare Plastique to Plastik to see the sharp lines around the buttons removed. Aside of lyrics. - The panel should use widget style of Qt even if the Qt style does not provide special style for Plasma. So the panel and other windows should always use the same style. - The icons on the desktop should use file manager, so it would be possible to make with desktop icons the same operations as with icons in file manager. - Should be possibility to disable all transparent plastic-like effects, for example those appearing when hovering over desktop icons. - Functionality of file manager shold be restored. For example, it was a surprise for me that there is no the very basic option "open each folder in a new window" in Dolphin. This function exists in KDE3, Nautilus, Windows, MacOS, OpenGEM, Seal, Ozone, CDE etc. In Konqueror this option appears but does not work (as of KDE 4.2). - Look of file manager should be restored. Difficult to describe but some of the things is too large distances between icons, annoying pictures apopearing when hovering a mouse over icons, selection with a bad-looking rectangle like in MinuetOS, bad looking tree view etc. - Ability to place on the desktop icons for special places such as Storage devices, Trash, Home, Network etc. I would like also port of KDE artwork such as Slick icon theme, Light Qt style etc. This is a screenshot of my desktop under Ubuntu Jaunty: http://www.linux.org.ru/gallery/3841036.png Now I do not use KDE because KDE3 from the semi-official repo caused problems with other packages and is incomplete. I am now considering to switch to another distro with better KDE3 support (such as SuSE of Alt Linux). From technical poit of view I'd like the window manager to provide the option 'sync to vblank' in the same way as Compiz does. Otherwise there is tearing on games and when moving windows. To day as I know only Compiz can do it in proper way.
