After reading all the great reviews of KDE 4.2, I ended up installing KDE 4.2 Beta 2 on my Arch Linux. 
So how does it feel…
Some of the problems which were bugging me on KDE 4.1 were slow responsiveness and lack of features when compared to KDE 3.5. Also the graphics performance was not that good with my nVidia GPU. These were the first things I wanted to be fixed in KDE 4.2.
Thankfully, KDE 4.2 fixes most if not all the problems in KDE 4.1. And if you experience graphics problem be sure to install the latest beta of the nVidia driver. (180.18 is the version available in AUR). The driver makes things on KDE 4.2 a lot smoother.
You can read a pretty nice review of KDE 4.2 Beta here and here along with some delicious looking screenshots. 
But in between all these improvements there are some things which are bugging me in KDE 4.2 Beta. 
- Plasma seems to be taking shape well with Plasma add-ons working pretty good now. But still Plasma keeps crashing every now and then. And everytime I go offline in Kopete, Plasma crashes.
- The new system tray is nice but it keeps flickering everytime I minimize or restore a window. I hope that is fixed before KDE 4.2 is released. Also the system tray icons seem a bit blurred at times.
- This one is not really KDE related but I dont like Amarok’s new look and feel. Hope the developers give the UI a second thought.
- I really hate KTorrent startup. It keeps on stacking notifications on top the system tray. Though the notifications are OK when I am copying or moving a file, KTorrent stacks at least 10 notifications when I open it.
- KDE 4.2 reminds me of Vista. The taskbar is too similar to the one in Windows Vista. Though KDE has been using that kind of taskbar even before Vista.
- Theming – KDE 4.2 appearance is not all that customizable.
These are not really negatives. May be I am just stuck with GNOME.
Hopefully I will try out KDE 4.2 final when it is out. For now I am back on GNOME 2.24 + Compiz Fusion.
Did you try KDE 4.2?
Jonas
31 Jan 09 at 7:32 am
I tried, and I had problems too. I had the flicker problem in system tray when I minimize/maximize an application. And I have problems with flickering in taskbar when I max/min windows apps.
h4p0
8 Feb 09 at 10:30 pm
Every thing in Kde 4.2 leaves a precarity sensation.
The tray icons flickering (not only on minimize but every 2-3 second: very annoying)
Plasma crashes are frequent and related to events of other damnly buggy apps like KOPETE (i hate it)
Millions of little windows of notifications appears on the screen even if completely unnecessary (eg. I have the amarok window ahead, I switch a song…and every f***’n time the OSD come out telling me the exact same information that I can read myself in the main window!)
Dolphin run in fullscreen at his discretion and there’s no way to move, resize or minimize the window because no window border is displayed
When I open more then 5-10 or more windows is a disaster of problems, in gnome i can open how many apps I want without problem.
Gnome was and remains always the better DE on linux.
h4p0
8 Feb 09 at 10:32 pm
…but yes, it’s visually cool…and improved a lot from the first relase.
Madison Brown
9 May 10 at 3:29 pm
Flicker is really great when sharing photos over friends and families. I love the resize feature of Flickr.*;:
Rubye Avallone
1 Aug 10 at 2:39 am
Good page content, makes the good work.