True, but frankly, KDE team repeatedly said that 4.0 to 4.2 is considered beta, and not production ready. I'm also coming from 3.5.x days, and just waited for KDE to mature a little before jumping 4.x bandwagon, and I'm still on KDE.
Maybe, we, the users shall read the announcements with a keener eye.
It states the following:
Some of the more obvious issues are listed below. If these issues are important to you, you should stay with KDE 3.5 (KDE 3.5.10 was released in August 2008) until KDE 4.2 is released (scheduled for release in January 2009) when most of these issues are scheduled to be resolved.
It is possible that distributions will work around some of these issues before distributing to users.
Also, IIRC, KDE developers were openly saying that releases from 4.0 to 4.2 will be buggy, and things will stabilize in 4.2 and beyond.[0]: https://community.kde.org/Schedules/Is_KDE_4.1_for_you%3F
That being said: I've been using KDE since the 1.x days, with only a short Ubuntu Unity-intermezzo around the 4.0 release. Most of that time, it's been great!
However I neither have the time, nor the desire to dig these places, yet alone logon to them.
Of course my mind may be lying to me, as well.
Anyway, these days are over and KDE is better than ever, so it’s only nitpicking over some trivia.