I’ve finally got round to installing the KDE version of Mandriva 2009.1 in a VM on my laptop. I’d been holding off, because I don’t really use KDE, and I wasn’t too impressed with how the other major distributions had implemented KDE4 (which is basically a total revision of every aspect). Happily, I can easily say that this is the most usable implementation of KDE4 I’ve ever come across, and it does a very good job of not getting in my way whilst still enabling me to be productive.
The desktop has seen some major customisations, as is usual with Mandriva (see http://www2.mandriva.com/ for a screen shot), and it actually looks and feels like a more polished version of KDE 3.5 (the last version of KDE I used for more than a couple of hours). There are sensible defaults, and I think the only application I would want to add is Thunderbird, because I still really don’t like Kmail.
But could I use it full time? Almost certainly yes, and if I wasn’t very tied to Gnome and the Gnome libraries and applications then I’d consider making the switch. As it is, I’ll happily keep it as a VM, which gives me the option to have a play with KDE4 every now and again without having to make any major life changes.