Download and Installation: Some anti-virus software might better be switched off while installing, then it's smooth.
First launch: No VST neither instruments nor fx. Closed it and launched again: The plugin routine started and worked heavily.
Some of the VSTs were found, but in case of instruments the sound libraries didn't come up. I'll have to find out where they are. That's strange, because all the VSTs are in the same VST folder that used to be effective for the "old" Sonar.
This applies only for some "minor" VSTIs, however, in some of my projects they play an important role, but are silent now. Will keep you up to date.
I like the dark surface actually, cause you see the clips and automation lanes better. They almost glow. (Don't need a lava lamp then

)
After the first shock, I had turned to ProTools, learned a lot which is also useful with Sonar. So I think I will keep a "parallel production line", some things might work better here, some others there. And most of the plugins which I became aware of in PT also work as VST, so I can use them either way. I am very happy to have the choice since Cakewalk is back.