I am now running a full KDE4 session, from a svn checkout from yesterday. That's 10+ days after the tagging of beta3, and at the current pace of bugfixing, this means a lot of improvements.

So what's it like? Here's the obligatory screenshot. You can see Okular annotating a .djvu file (of course it also works with .pdf files) and Marble, which is a bit like Google Earth except that it can be embedded in any KDE4 app, which opens endless possibilities. You can also see the Battery plasmoid, which reacts instantly when you plug/unplug your laptop, and the Pager plasmoid, which works just as in KDE3. KWin defaulted to using OpenGL for compositing, and it works great here. Slamming the mouse to the top-right corner triggers the very useful Present Windows effect.

For me it's all perfectly usable, so I'm staying under KDE4 full-time. Not only to help with beta-testing (I already filed this bug report), but really because it already is stable and complete enough for me to use as my main desktop. I'm still using some KDE3 apps in my KDE4 session, but that's not a problem at all -- though of course it would be nice to use only KDE4 apps eventually.

On another note, Eigen2 development has been very fast recently, but more on this later -- for now the top priority for us all should be to help as we can to get 4.0 in shape, and Eigen2 will only be used in KDE 4.1 and KOffice 2.1. So I try to compensate for my current non-contribution to the 4.0 effort by doing some beta-testing, bug-reporting, and encouraging you all to do so :)