This is something I find very annoying with Ubuntu. Every time something new arrives you need to wait for the next release until you can try it. It feels stupid that I would probably stick to 4.0 when 4.1 has arrived if I keep using the current Ubuntu, when obviously 4.1 will be a Huge improvement.. I guess it's time to update to the Intrepid Ibex development version soon then..
Well I have been using KDE 4.1 svn/trunk since February (I was using KDE 4.0.2 only at the time, without any other DE installed, and it was unsuitable for everyday tasks so I upgraded : D).
I am excited about all the progress it has made and that it will make in the future.
Plasma is great right now (+the panel handling is very intuitive), Konqui rocks and so does Amarok 2. I hated the idea of Dolphin replacing Konqueror but know I really like dolphin. Nonetheless I miss Kaffeine.
There are still bugs, but I use it *everyday* now. When it comes out officially it will be rock-solid.