Well, after some testing the temporary verdict:
Installation Progress is not the fastest but it's fully automatic and works.
Booting time improved for me a Little bit more than it already did with Windows 8.
All programs I have seem to work.
Only tried Witcher 3 yet and it runs as well as it did before the upgrade. I have the subjective Impression that it even gained a few fps. I'm probably wrong cuz I don't know any reason why it should.
The IE works like a charm. Quick loading of pages, no kickups while Scrolling Content heavy pages. Only the dictionary is not Setup for English yet, hence the weird capitals in here
Wifi Connection worked instantly.
Overall it runs very well and I like what I see. No Problems whatsoever. Guess I'll Keep it till I get a full Windows 10 key and can do a clean full install.