I am using KDE 4.2RC1 since 2 weeks now, mainly 2 to 3 working day at the office, and has not experienced any crash yet or having any regret by using it. The desktop is just great, and very polished.
To install it in OpenSuse 11.1, just use the following link
Or you can choose to install a more basic KDE 4 desktop.Attention: The KDE:KDE4:Factory:Desktop Build Service project offers KDE 4.2.x packages as they are currently under development for openSUSE 11.2. They should be mostly usable, but have bugs.