Today, I have installed KDE4 to look at what has changed. I am mainly a GNOME and xfce user, but I have gotten interested in the new KDE.
So I installed it, opened it up and tried it out a bit. To me it seemed a bit slow and I had some minor graphical problems, meaning that something did not look really good.
Then I began trying out all of those K* programs. When I tried out KMail on my AOL IMAP, it immediately marked all of my email as spam, thus moving it to a local spam folder.
As none of it was really spam, I tried moving it back to the Inbox, which failed. Then I moved it into an empty folder, which took about 15 minutes all in all.
My initial experience with KDE4 therefore is not really a good one. I'll maybe play around with it later, but I won't let it touch my email account for now ;)