I have built plama 5 (on Cauldron) following instructions on
https://community.kde.org/Frameworks/BuildingSome additional adjustments were needed since i used /opt/kf5/kde_frameworks prefix.
Not all is complete yet in Plasma 5.0.
At first i had flickering while scrolling, but after choosing OpenGL 3.1 and EGL for compositiong all seems well (using AMD opensource drivers)
For some reason right click does not work in konsole.
MCC can not be opened from menu. No password dialog opens, but launching from konsole works.
Translations are not complete, most apps are not ported yet
Plasma 5.0 should not be default on any distro. To use it as default plasma version should be > 5.1, but it is probably released too late to be incuded in Mageia 5 (Versions freeze 2014/09/09, Plasma 5.1 expected relase date is 2014/10/15)