Have been using KDE 4.1 beta 2 for quite a few days now. I'm using the Kubuntu packages on Kubuntu 8.04. No complaints this time. The software is definitely ready to be used on a daily basis. Of course, this is beta so things are still a big buggy but I'm sure they will sort it out over time. Here's a screenshot.
1. Dolphin - Dolphin has matured and is acting as a good supplement for Konqueror. The good thing is, folder display in Konqueror-KDE4 is being handled by dolphinpart so that you get all the feature that dolphin had to offer (in terms of folder view) inside of Konqueror. However, Dolphin is still rather buggy and mine crashes too many times. I do hope they fix this soon.
2. Dragon Player - This is still in baby stages. Not much functionality here, although it plays all of my video files effortlessly. The screen blanks out if even part of it is occluded by another window. I'm not sure if it's a bug or just something that compiz-fusion is causing. In any case, not very usable just now.
3. Okular - This is probably the most mature part of KDE4. It has good functionality, is very stable and usable. I use it to read PDFs and CBRs and have found it much better than all other softwares I use. One, it is fast. Comic Book Reader on windows lurches when I scroll images. Okular doesn't. Adobe acrobat lurches when loading big PDFs, Okular doesn't. What we have to wait for are more plugins to display all sort of obscure file formats. :)
4. Gwenview - Again, quite mature, stable, and usable. Excellent image viewing software.
5. Plasma - this is where KDE4 loses out. Plasma is still VERY buggy, and not very funtional. And frankly, I don't see the point of all this paraphernalia. The only think I liked, was it's capability to run Superkaramba widgets seamlessly. There's some talk about it being able to run OSX widgets too but haven't tried that out. Plasma needs to mature a bit more.
One the whole, I like KDE4. The developers have done some very radical things. I don't understand the whole opposition that they are facing. Yes, the changes are radical and users will take time to get used to it, but hey, isn't that very much in the spirit of free software? People should try out new things and users should always have the option. If you don't like KDE4 then use KDE3!
Where KDE4 went wrong was in its marketing. The users assumed, understandably so, that KDE4 was KDE3 + something, which it isn't. It's a whole new desktop environment, really. The whole experience is nothing like KDE3. And keeping that in mind, KDE4.1 beta 2 is more like 0.1 beta 2 of some totally new software. For just the second release of a new software, it is awesome!