Even if a particular program has a version for KDE 4, you should also spend some time examining some of the changes in it. You may notice, for example, that the Kate text editor now has a desktop widget (that is, applet) for starting it in different ways. Dolphin, too, has undergone some changes from earlier versions, including the ability to navigate a version repository, encrypt folders on their contents, and use the contents of a selected folder to run a desktop slide show. Some will find these new features welcome while others, no doubt, will find them unnecessary clutter.
Still other programs are entirely new. Introduced in version 4.0, Okular and Gwenview, the new document and picture viewers, bring a much-need consolidation of viewers to KDE, while 4.1 introduces KSCD, a CD player, and Dragon Player, a DVD player, as well as a number of games such as KDiamond and KBreakout. Few of these new programs are essential to most people, but you should scan the 4.1 release notes to see whether any of them might affect your decision whether to migrate to the new release.
With all these changes, it will probably take a few days before you overcome your sense of the news and get an accurate impression of KDE 4.1 as a whole. In some cases, you may not notice much at all -- for instance, the ability to tag and comment on files will only come into its own in later releases as other features are added to allow you to take full advantage of Nepomuk, the semantic desktop layer. However, the general appearance and performance should become obvious to any user.
To start with, KDE 4 marks a major change in appearance for the desktop. In the KDE 4 releases, the desktop has finally struggled out of its late Nineties look with photo-realistic icons and desktop themes, and a compositing effects for those whose video cards and drivers can run them. Eye-candy may not be everything, and no doubt some will complain that KDE looks too much like Windows Vista or Mac OS X, but this changed appearance should gain KDE new respect in many circles.
In addition, the desktop is rendered in scalable vector graphics. Besides enhancing the eye-candy, this change has the practical effect of allowing you to rescale windows quickly without distortion. This feature could very easily be considered an accessibility feature, and even users with normal eyesight may welcome it at the end of a long day in front of the screen.
Another point that has been overlooked is the growing consistency of interfaces in the KDE 4 series. KDE has always had less variation in its menus and windows than GNOME, but now, with programs like Dolphin and Konqueror drawing on some of the same utilities, such as the Find File tool, the consistency is more obvious than ever. In fact, it may make KDE 4's innovations easier to learn than you might initially imagine.
Most importantly, general performance in 4.1 seems brisker than in KDE 3, and stability is considerably improved, not only only compared to KDE 4.0, but compared to the beta releases of a few weeks ago.
From this high level view, much of the controversy ceases to exist. So far as look and performance goes, KDE 4.1 is not only ready for use but can lay a serious claim to setting the standard for all modern desktops.
KDE 4.1 has enough gaps in customization and supporting applications that it will probably not stop the controversy that surrounded KDE 4.0. However, it does offer enough features and stability that it should reduce the ferocity and number of complaints enough that more serious assessment of the changes in KDE 4.1 can begin.
Speaking as someone who has used KDE 4 intermittently since January and almost daily in the last month, I suggest that this stage is long overdue. One of the most unfortunate aspects of the recent user revolt is that it has all but obscured how ambitious and innovative the KDE 4 series actually is.
That is not to say that some complaints were unjustified, or that every experiment in KDE 4 is equally successful. But it does mean that serious assessment has been lost as emotion and rumor have taken on a life of their own.
With luck, KDE 4.1 will provide enough breathing space that more thoughtful criticism can start to emerge. If it does that, then KDE 4.1 will be a successful release -- even if it doesn't offer everything that every user wants.