So I've been using KDE 4.5 since the evening it came out. I don't know what it is about every time the KDE claims "this is a stabilizing release" but it seems to be the opposite of my experience. This is easily the buggiest point release of KDE since their last "stabilizing release" of KDE 4.3.
Now admittedly, the list of bugs is small... but they are hitting my hard and frequently. Very frequently. Usually about 12 to 20 times a day. I am hoping (and I'm pretty certain) these bugs are just for my installation.
Konqueror: I use Konqueror as my file manager, and since the upgrade about twice an hour it has a total lockup/total freeze for a duration of anywhere from 10 to 60 seconds. It's pretty horrendous sometimes. It also won't let me close tabs on occasion. There have been some more minor but less frequent bugs but I lost track.
User management: I cannot add a new user to my system, at least not through the GUIs nicely provided by KDE. I wanted to add a new one so I could check his default Konqueror configuration settings against my own. BUT creating a user is proving problematic, since after I create one and set it's password, I switch sessions to log in with it. However, at the login screen it asks me to change the password (root required) it says. HOWEVER YOU CANNOT TYPE ANYTHING INTO THE BOX. At first I thought it was an error with my wireless USB keyboard, so grumbling I plugged in a wired keyboard, but it actually made it worse (the mouse cursor stopped working when I did that). So I cannot log in with the new user I created. That's.... pretty hilariously bad.
Plasma: Presenting all Windows is slow. I don't know why because everything else seems better. This is a pretty minor bug because it does not really impair functionality, mostly. Sometimes it is so slow the cursor doesn't reach the correct window in time when enter is pressed or the window is clicked
Klipper: It stays open after you select some previous entry. It stays this way unless you click it closed. Perhaps this is a feature?