I don't want to spend ages configuring. Glitches included a list of problems I included in a previous thread. Sorry but it does NOT look slick at all, the graphics look dated. I used 3.5, then switched to xfce4, then to Gnome, then to KDE 4.0, then at 4.3 switched to Unity. If it wasn't for the spyware I would definitely be sticking to Unity, it looks very polished and is easy to use. I played with KDE at Christmas and tried shifting a guinea pig family member to it even, but ended up switching all the machines to Linux Mint. So far Mint looks like my target when I reformat, though it's not my ideal desktop.
I love the idea of KDE, it pleases me technically, but take at look at the screenshot (I would like to say screenshots but there is only one): the mess of Dolphin, the Windows95 task bar. Now compare it to Unity (amazing interactive demo, as well as slick looking desktop), or these themes for the still immature Cinnamon and compare it to kde-look.org.
I've written apps using QT, it's very nice. But as a desktop it's got a hell of a long way to go.