Ars Technica has a detailed review of the current kde 4.0 release. They are covering the new technologies but also the user experience with the new user interface system plasma.
I think they are right with their resumee.
The level of incompleteness apparent in the 4.0 release has, unsurprisingly, drawn heavy criticism from end users here in our forums and elsewhere on the Internet. Several longtime KDE enthusiasts in Ars Technica’s Linux community are particularly disappointed with the extent to which KDE 4.0 falls short of the promised vision.
I’m excited about the possibilities created by Plasma, Solid, and other new features in the KDE architecture, and I’m looking forward to seeing how they help the desktop evolve. I submitted a handful of bug reports while writing this article; developers responded almost immediately. If their diligence and rapid bug resolution rate is any indication, then I think we can be confident that future releases will meet or exceed expectations.
So I share the opinion with them, that kde 4.0 is for enthusiasts and early adopters. Having solid and innovative technical infrastructure help creating great software. Which I’m sure kde 4 will evolve into.