This weekend I upgraded my system to Plasma 5.1 beta on OpenSuse. Mostly, the system works fine. Only two issues are a bit unpleasant.
1. The Look&Feel of Libreoffice is really ugly and does not fit anymore, even not to kde4-look. Is this normal for the early time of Plasma5 or disto-specific?

2. I get random freezes of the system and up to now have no idea about the reason. I already tried to kill plasmashell from a console, but only a hard reset is helping.

Any ideas on these issues? I would be really grateful!

The first issue happens because LibreOffice does not detect Plasma5 as KDE. You can force the KDE style by exporting OOO_FORCE_DESKTOP=kde

Put:

export SAL_USE_VCLPLUGIN=kde4

in your .profile file (or .zprofile if using zsh) and log off/on to get the correct theming .

For random freezing, doing an alt-tab seems to make Plasma responsive again. I think it is because of my old Intel GPU (Intel GM4500)