I decided to take some risk and upgrade to KDE 4.6 Beta 2 on my workstation and also on my laptop. So far, i don't see major problems, but i do notes some bugs.
The first one is when i plug USB flash drive, instead of getting one device, i get two. Probably that's because i didn't disable HAL yet. I haven't tried to disable it, but it's a minor problem so i will skip that.
In Konqueror, i can't save preference, for example proxy settings. When i close the preference dialog and reopen it again, it rolls back to the default settings. Since my Internet access is behind a proxy, i couldn't browse using Konqueror. Actually it's not a major problem as well, as it's not my default browser, but i wanted to test the new KWebKitPart that Eric has provided for Konqueror.
So far, i'm quite satisfied with KDE 4.6 Beta 2. Hoping to see better KDE release in the future and the final version in January